fix: 修复定时任务模块问题

1. 修复 SDK 文档 API 路由顺序问题
   - 将静态路由 /sdk-docs, /test-script, /secrets 移到动态路由 /{task_id} 之前
   - 解决 "请求参数验证失败" 错误

2. 优化错误页面体验
   - 使用 sessionStorage 传递错误信息，URL 保持干净
   - 使用 router.replace 替代 push，浏览器返回不会停留在错误页
   - 记录来源页面，支持正确返回

3. 增强网络错误处理
   - 区分超时、网络错误、服务不可用
   - 后端未启动时显示友好的 "服务暂时不可用" 提示

4. 添加定时任务模块文档

backend/app/routers/tasks.py

@@ -75,6 +75,191 @@ class TestScriptRequest(BaseModel):
     params: Optional[dict] = None
 
 
+# ==================== Static Routes (must be before dynamic routes) ====================
+
+@router.get("/sdk-docs")
+async def get_sdk_docs():
+    """获取SDK文档"""
+    return {
+        "functions": [
+            {
+                "name": "log",
+                "signature": "log(message: str, level: str = 'INFO')",
+                "description": "记录日志",
+                "example": "log('处理完成', 'INFO')"
+            },
+            {
+                "name": "print",
+                "signature": "print(*args)",
+                "description": "打印输出",
+                "example": "print('Hello', 'World')"
+            },
+            {
+                "name": "ai",
+                "signature": "ai(prompt: str, system: str = None, model: str = None, temperature: float = 0.7)",
+                "description": "调用AI模型",
+                "example": "result = ai('生成一段问候语', system='你是友善的助手')"
+            },
+            {
+                "name": "dingtalk",
+                "signature": "dingtalk(webhook: str, content: str, title: str = None, at_all: bool = False)",
+                "description": "发送钉钉消息",
+                "example": "dingtalk(webhook_url, '# 标题\\n内容')"
+            },
+            {
+                "name": "wecom",
+                "signature": "wecom(webhook: str, content: str, msg_type: str = 'markdown')",
+                "description": "发送企微消息",
+                "example": "wecom(webhook_url, '消息内容')"
+            },
+            {
+                "name": "http_get",
+                "signature": "http_get(url: str, headers: dict = None, params: dict = None)",
+                "description": "发起GET请求",
+                "example": "resp = http_get('https://api.example.com/data')"
+            },
+            {
+                "name": "http_post",
+                "signature": "http_post(url: str, data: any = None, headers: dict = None)",
+                "description": "发起POST请求",
+                "example": "resp = http_post('https://api.example.com/submit', {'key': 'value'})"
+            },
+            {
+                "name": "db_query",
+                "signature": "db_query(sql: str, params: dict = None)",
+                "description": "执行只读SQL查询",
+                "example": "rows = db_query('SELECT * FROM users WHERE status = :status', {'status': 1})"
+            },
+            {
+                "name": "get_var",
+                "signature": "get_var(key: str, default: any = None)",
+                "description": "获取持久化变量",
+                "example": "counter = get_var('counter', 0)"
+            },
+            {
+                "name": "set_var",
+                "signature": "set_var(key: str, value: any)",
+                "description": "设置持久化变量",
+                "example": "set_var('counter', counter + 1)"
+            },
+            {
+                "name": "del_var",
+                "signature": "del_var(key: str)",
+                "description": "删除持久化变量",
+                "example": "del_var('temp_data')"
+            },
+            {
+                "name": "get_param",
+                "signature": "get_param(key: str, default: any = None)",
+                "description": "获取任务参数",
+                "example": "prompt = get_param('prompt', '默认提示词')"
+            },
+            {
+                "name": "get_params",
+                "signature": "get_params()",
+                "description": "获取所有任务参数",
+                "example": "params = get_params()"
+            },
+            {
+                "name": "get_tenants",
+                "signature": "get_tenants(app_code: str = None)",
+                "description": "获取租户列表",
+                "example": "tenants = get_tenants('notification-service')"
+            },
+            {
+                "name": "get_tenant_config",
+                "signature": "get_tenant_config(tenant_id: str, app_code: str, key: str = None)",
+                "description": "获取租户的应用配置",
+                "example": "webhook = get_tenant_config('tenant1', 'notification-service', 'dingtalk_webhook')"
+            },
+            {
+                "name": "get_all_tenant_configs",
+                "signature": "get_all_tenant_configs(app_code: str)",
+                "description": "获取所有租户的应用配置",
+                "example": "configs = get_all_tenant_configs('notification-service')"
+            },
+            {
+                "name": "get_secret",
+                "signature": "get_secret(key: str)",
+                "description": "获取密钥（优先租户级）",
+                "example": "api_key = get_secret('api_key')"
+            }
+        ],
+        "variables": [
+            {"name": "task_id", "description": "当前任务ID"},
+            {"name": "tenant_id", "description": "当前租户ID"},
+            {"name": "trace_id", "description": "当前执行追踪ID"}
+        ],
+        "libraries": [
+            {"name": "json", "description": "JSON处理"},
+            {"name": "re", "description": "正则表达式"},
+            {"name": "math", "description": "数学函数"},
+            {"name": "random", "description": "随机数"},
+            {"name": "hashlib", "description": "哈希函数"},
+            {"name": "base64", "description": "Base64编解码"},
+            {"name": "datetime", "description": "日期时间处理"},
+            {"name": "timedelta", "description": "时间差"},
+            {"name": "urlencode/quote/unquote", "description": "URL编码"}
+        ]
+    }
+
+
+@router.post("/test-script")
+async def test_script(data: TestScriptRequest, db: Session = Depends(get_db)):
+    """测试脚本执行"""
+    executor = ScriptExecutor(db)
+    result = executor.test_script(
+        script_content=data.script_content,
+        task_id=0,
+        tenant_id=data.tenant_id,
+        params=data.params
+    )
+    return result
+
+
+@router.get("/secrets")
+async def list_secrets(
+    tenant_id: Optional[str] = None,
+    db: Session = Depends(get_db)
+):
+    """获取密钥列表"""
+    query = db.query(Secret)
+    if tenant_id:
+        query = query.filter(Secret.tenant_id == tenant_id)
+    
+    items = query.order_by(desc(Secret.created_at)).all()
+    
+    return {
+        "items": [
+            {
+                "id": s.id,
+                "tenant_id": s.tenant_id,
+                "secret_key": s.secret_key,
+                "description": s.description,
+                "created_at": s.created_at,
+                "updated_at": s.updated_at
+            }
+            for s in items
+        ]
+    }
+
+
+@router.post("/secrets")
+async def create_secret(data: SecretCreate, db: Session = Depends(get_db)):
+    """创建密钥"""
+    secret = Secret(
+        tenant_id=data.tenant_id,
+        secret_key=data.secret_key,
+        secret_value=data.secret_value,
+        description=data.description
+    )
+    db.add(secret)
+    db.commit()
+    db.refresh(secret)
+    
+    return {"success": True, "id": secret.id}
+
+
 # ==================== Task CRUD ====================
 
 @router.get("")
@@ -272,194 +457,7 @@ async def get_task_logs(
     }
 
 
-# ==================== Script Testing ====================
-
-@router.post("/test-script")
-async def test_script(data: TestScriptRequest, db: Session = Depends(get_db)):
-    """测试脚本执行"""
-    executor = ScriptExecutor(db)
-    result = executor.test_script(
-        script_content=data.script_content,
-        task_id=0,
-        tenant_id=data.tenant_id,
-        params=data.params
-    )
-    return result
-
-
-# ==================== SDK Documentation ====================
-
-@router.get("/sdk-docs")
-async def get_sdk_docs():
-    """获取SDK文档"""
-    return {
-        "functions": [
-            {
-                "name": "log",
-                "signature": "log(message: str, level: str = 'INFO')",
-                "description": "记录日志",
-                "example": "log('处理完成', 'INFO')"
-            },
-            {
-                "name": "print",
-                "signature": "print(*args)",
-                "description": "打印输出",
-                "example": "print('Hello', 'World')"
-            },
-            {
-                "name": "ai",
-                "signature": "ai(prompt: str, system: str = None, model: str = None, temperature: float = 0.7)",
-                "description": "调用AI模型",
-                "example": "result = ai('生成一段问候语', system='你是友善的助手')"
-            },
-            {
-                "name": "dingtalk",
-                "signature": "dingtalk(webhook: str, content: str, title: str = None, at_all: bool = False)",
-                "description": "发送钉钉消息",
-                "example": "dingtalk(webhook_url, '# 标题\\n内容')"
-            },
-            {
-                "name": "wecom",
-                "signature": "wecom(webhook: str, content: str, msg_type: str = 'markdown')",
-                "description": "发送企微消息",
-                "example": "wecom(webhook_url, '消息内容')"
-            },
-            {
-                "name": "http_get",
-                "signature": "http_get(url: str, headers: dict = None, params: dict = None)",
-                "description": "发起GET请求",
-                "example": "resp = http_get('https://api.example.com/data')"
-            },
-            {
-                "name": "http_post",
-                "signature": "http_post(url: str, data: any = None, headers: dict = None)",
-                "description": "发起POST请求",
-                "example": "resp = http_post('https://api.example.com/submit', {'key': 'value'})"
-            },
-            {
-                "name": "db_query",
-                "signature": "db_query(sql: str, params: dict = None)",
-                "description": "执行只读SQL查询",
-                "example": "rows = db_query('SELECT * FROM users WHERE status = :status', {'status': 1})"
-            },
-            {
-                "name": "get_var",
-                "signature": "get_var(key: str, default: any = None)",
-                "description": "获取持久化变量",
-                "example": "counter = get_var('counter', 0)"
-            },
-            {
-                "name": "set_var",
-                "signature": "set_var(key: str, value: any)",
-                "description": "设置持久化变量",
-                "example": "set_var('counter', counter + 1)"
-            },
-            {
-                "name": "del_var",
-                "signature": "del_var(key: str)",
-                "description": "删除持久化变量",
-                "example": "del_var('temp_data')"
-            },
-            {
-                "name": "get_param",
-                "signature": "get_param(key: str, default: any = None)",
-                "description": "获取任务参数",
-                "example": "prompt = get_param('prompt', '默认提示词')"
-            },
-            {
-                "name": "get_params",
-                "signature": "get_params()",
-                "description": "获取所有任务参数",
-                "example": "params = get_params()"
-            },
-            {
-                "name": "get_tenants",
-                "signature": "get_tenants(app_code: str = None)",
-                "description": "获取租户列表",
-                "example": "tenants = get_tenants('notification-service')"
-            },
-            {
-                "name": "get_tenant_config",
-                "signature": "get_tenant_config(tenant_id: str, app_code: str, key: str = None)",
-                "description": "获取租户的应用配置",
-                "example": "webhook = get_tenant_config('tenant1', 'notification-service', 'dingtalk_webhook')"
-            },
-            {
-                "name": "get_all_tenant_configs",
-                "signature": "get_all_tenant_configs(app_code: str)",
-                "description": "获取所有租户的应用配置",
-                "example": "configs = get_all_tenant_configs('notification-service')"
-            },
-            {
-                "name": "get_secret",
-                "signature": "get_secret(key: str)",
-                "description": "获取密钥（优先租户级）",
-                "example": "api_key = get_secret('api_key')"
-            }
-        ],
-        "variables": [
-            {"name": "task_id", "description": "当前任务ID"},
-            {"name": "tenant_id", "description": "当前租户ID"},
-            {"name": "trace_id", "description": "当前执行追踪ID"}
-        ],
-        "libraries": [
-            {"name": "json", "description": "JSON处理"},
-            {"name": "re", "description": "正则表达式"},
-            {"name": "math", "description": "数学函数"},
-            {"name": "random", "description": "随机数"},
-            {"name": "hashlib", "description": "哈希函数"},
-            {"name": "base64", "description": "Base64编解码"},
-            {"name": "datetime", "description": "日期时间处理"},
-            {"name": "timedelta", "description": "时间差"},
-            {"name": "urlencode/quote/unquote", "description": "URL编码"}
-        ]
-    }
-
-
-# ==================== Secrets ====================
-
-@router.get("/secrets")
-async def list_secrets(
-    tenant_id: Optional[str] = None,
-    db: Session = Depends(get_db)
-):
-    """获取密钥列表"""
-    query = db.query(Secret)
-    if tenant_id:
-        query = query.filter(Secret.tenant_id == tenant_id)
-    
-    items = query.order_by(desc(Secret.created_at)).all()
-    
-    return {
-        "items": [
-            {
-                "id": s.id,
-                "tenant_id": s.tenant_id,
-                "secret_key": s.secret_key,
-                "description": s.description,
-                "created_at": s.created_at,
-                "updated_at": s.updated_at
-            }
-            for s in items
-        ]
-    }
-
-
-@router.post("/secrets")
-async def create_secret(data: SecretCreate, db: Session = Depends(get_db)):
-    """创建密钥"""
-    secret = Secret(
-        tenant_id=data.tenant_id,
-        secret_key=data.secret_key,
-        secret_value=data.secret_value,
-        description=data.description
-    )
-    db.add(secret)
-    db.commit()
-    db.refresh(secret)
-    
-    return {"success": True, "id": secret.id}
-
+# ==================== Secrets (dynamic routes) ====================
 
 @router.put("/secrets/{secret_id}")
 async def update_secret(secret_id: int, data: SecretUpdate, db: Session = Depends(get_db)):