feat: 员工同步配置支持多租户

- 后端新增员工同步配置API（获取/保存/测试连接）
- employee_sync_service 从数据库读取配置
- 前端系统设置页面添加"员工同步"Tab
- 支持配置：数据库主机、端口、库名、用户名、密码、表名
- 保留默认配置用于向后兼容

backend/app/services/employee_sync_service.py

@@ -23,17 +23,59 @@ logger = get_logger(__name__)
 class EmployeeSyncService:
     """员工同步服务"""
     
-    # 外部数据库连接配置
-    EXTERNAL_DB_URL = "mysql+aiomysql://neuron_new:NWxGM6CQoMLKyEszXhfuLBIIo1QbeK@120.77.144.233:29613/neuron_new?charset=utf8mb4"
+    # 默认外部数据库连接配置（向后兼容）
+    DEFAULT_DB_URL = "mysql+aiomysql://neuron_new:NWxGM6CQoMLKyEszXhfuLBIIo1QbeK@120.77.144.233:29613/neuron_new?charset=utf8mb4"
+    DEFAULT_TABLE_NAME = "v_钉钉员工表"
     
-    def __init__(self, db: AsyncSession):
+    def __init__(self, db: AsyncSession, tenant_id: int = 1):
         self.db = db
+        self.tenant_id = tenant_id
         self.external_engine = None
+        self.table_name = self.DEFAULT_TABLE_NAME
+        self._db_url = None
+    
+    async def _get_config_from_db(self) -> tuple:
+        """从数据库获取员工同步配置"""
+        result = await self.db.execute(
+            text("""
+                SELECT config_key, config_value 
+                FROM tenant_configs 
+                WHERE tenant_id = :tenant_id AND config_group = 'employee_sync'
+            """),
+            {"tenant_id": self.tenant_id}
+        )
+        rows = result.fetchall()
+        
+        config = {}
+        for key, value in rows:
+            config[key] = value
+        
+        return config
+    
+    async def _build_db_url(self) -> str:
+        """构建数据库连接URL"""
+        config = await self._get_config_from_db()
+        
+        db_host = config.get('DB_HOST')
+        db_port = config.get('DB_PORT')
+        db_name = config.get('DB_NAME')
+        db_user = config.get('DB_USER')
+        db_password = config.get('DB_PASSWORD')
+        self.table_name = config.get('TABLE_NAME') or self.DEFAULT_TABLE_NAME
+        
+        # 如果配置完整，使用配置的URL
+        if all([db_host, db_port, db_name, db_user, db_password]):
+            return f"mysql+aiomysql://{db_user}:{db_password}@{db_host}:{db_port}/{db_name}?charset=utf8mb4"
+        
+        # 否则使用默认配置
+        logger.warning(f"租户 {self.tenant_id} 未配置员工同步数据库，使用默认配置")
+        return self.DEFAULT_DB_URL
         
     async def __aenter__(self):
         """异步上下文管理器入口"""
+        self._db_url = await self._build_db_url()
         self.external_engine = create_async_engine(
-            self.EXTERNAL_DB_URL,
+            self._db_url,
             echo=False,
             pool_pre_ping=True,
             pool_recycle=3600
@@ -52,9 +94,9 @@ class EmployeeSyncService:
         Returns:
             员工数据列表
         """
-        logger.info("开始从钉钉员工表获取数据...")
+        logger.info(f"开始从员工表 {self.table_name} 获取数据...")
         
-        query = """
+        query = f"""
         SELECT 
             员工姓名,
             手机号,
@@ -67,7 +109,7 @@ class EmployeeSyncService:
             钉钉用户ID,
             入职日期,
             工作地点
-        FROM v_钉钉员工表
+        FROM {self.table_name}
         WHERE 是否在职 = 1
         ORDER BY 员工姓名
         """