feat: 新增告警、成本、配额、微信模块及缓存服务

- 新增告警模块 (alerts): 告警规则配置与触发
- 新增成本管理模块 (cost): 成本统计与分析
- 新增配额模块 (quota): 配额管理与限制
- 新增微信模块 (wechat): 微信相关功能接口
- 新增缓存服务 (cache): Redis 缓存封装
- 新增请求日志中间件 (request_logger)
- 新增异常处理和链路追踪中间件
- 更新 dashboard 前端展示
- 更新 SDK stats_client 功能

backend/app/middleware/trace.py

@@ -0,0 +1,114 @@
+"""
+TraceID 追踪中间件
+
+为每个请求生成唯一的 TraceID，用于日志追踪和问题排查。
+
+功能：
+- 自动生成 TraceID（或从请求头获取）
+- 注入到响应头 X-Trace-ID
+- 提供上下文变量供日志使用
+- 支持请求耗时统计
+"""
+import time
+import uuid
+import logging
+from contextvars import ContextVar
+from typing import Optional
+from starlette.middleware.base import BaseHTTPMiddleware
+from starlette.requests import Request
+from starlette.responses import Response
+
+logger = logging.getLogger(__name__)
+
+# 上下文变量存储当前请求的 TraceID
+_trace_id_var: ContextVar[Optional[str]] = ContextVar("trace_id", default=None)
+
+# 请求头名称
+TRACE_ID_HEADER = "X-Trace-ID"
+REQUEST_ID_HEADER = "X-Request-ID"
+
+
+def get_trace_id() -> str:
+    """获取当前请求的 TraceID"""
+    trace_id = _trace_id_var.get()
+    return trace_id if trace_id else "no-trace"
+
+
+def set_trace_id(trace_id: str) -> None:
+    """设置当前请求的 TraceID"""
+    _trace_id_var.set(trace_id)
+
+
+def generate_trace_id() -> str:
+    """生成新的 TraceID，格式: 时间戳-随机8位"""
+    timestamp = int(time.time())
+    random_part = uuid.uuid4().hex[:8]
+    return f"{timestamp}-{random_part}"
+
+
+class TraceMiddleware(BaseHTTPMiddleware):
+    """TraceID 追踪中间件"""
+    
+    def __init__(self, app, log_requests: bool = True):
+        super().__init__(app)
+        self.log_requests = log_requests
+    
+    async def dispatch(self, request: Request, call_next) -> Response:
+        # 从请求头获取 TraceID，或生成新的
+        trace_id = (
+            request.headers.get(TRACE_ID_HEADER) or
+            request.headers.get(REQUEST_ID_HEADER) or
+            generate_trace_id()
+        )
+        
+        set_trace_id(trace_id)
+        
+        start_time = time.time()
+        method = request.method
+        path = request.url.path
+        
+        if self.log_requests:
+            logger.info(f"[{trace_id}] --> {method} {path}")
+        
+        try:
+            response = await call_next(request)
+            duration_ms = int((time.time() - start_time) * 1000)
+            
+            response.headers[TRACE_ID_HEADER] = trace_id
+            response.headers["X-Response-Time"] = f"{duration_ms}ms"
+            
+            if self.log_requests:
+                logger.info(f"[{trace_id}] <-- {response.status_code} ({duration_ms}ms)")
+            
+            return response
+            
+        except Exception as e:
+            duration_ms = int((time.time() - start_time) * 1000)
+            logger.error(f"[{trace_id}] !!! 请求异常: {e} ({duration_ms}ms)")
+            raise
+
+
+class TraceLogFilter(logging.Filter):
+    """日志过滤器：自动添加 TraceID"""
+    
+    def filter(self, record):
+        record.trace_id = get_trace_id()
+        return True
+
+
+def setup_logging(level: int = logging.INFO, include_trace: bool = True):
+    """配置日志格式"""
+    if include_trace:
+        format_str = "%(asctime)s [%(trace_id)s] %(levelname)s %(name)s: %(message)s"
+    else:
+        format_str = "%(asctime)s %(levelname)s %(name)s: %(message)s"
+    
+    handler = logging.StreamHandler()
+    handler.setFormatter(logging.Formatter(format_str, datefmt="%Y-%m-%d %H:%M:%S"))
+    
+    if include_trace:
+        handler.addFilter(TraceLogFilter())
+    
+    root_logger = logging.getLogger()
+    root_logger.setLevel(level)
+    root_logger.handlers = [handler]