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/exception_handler.py

@@ -0,0 +1,128 @@
+"""
+统一异常处理
+
+捕获所有异常，返回统一格式的错误响应，包含 TraceID。
+"""
+import logging
+import traceback
+from typing import Union
+from fastapi import FastAPI, Request, HTTPException
+from fastapi.responses import JSONResponse
+from fastapi.exceptions import RequestValidationError
+from starlette.exceptions import HTTPException as StarletteHTTPException
+
+from .trace import get_trace_id
+
+logger = logging.getLogger(__name__)
+
+
+class ErrorCode:
+    """错误码常量"""
+    BAD_REQUEST = "BAD_REQUEST"
+    UNAUTHORIZED = "UNAUTHORIZED"
+    FORBIDDEN = "FORBIDDEN"
+    NOT_FOUND = "NOT_FOUND"
+    VALIDATION_ERROR = "VALIDATION_ERROR"
+    RATE_LIMITED = "RATE_LIMITED"
+    INTERNAL_ERROR = "INTERNAL_ERROR"
+    SERVICE_UNAVAILABLE = "SERVICE_UNAVAILABLE"
+    GATEWAY_ERROR = "GATEWAY_ERROR"
+
+
+STATUS_TO_ERROR_CODE = {
+    400: ErrorCode.BAD_REQUEST,
+    401: ErrorCode.UNAUTHORIZED,
+    403: ErrorCode.FORBIDDEN,
+    404: ErrorCode.NOT_FOUND,
+    422: ErrorCode.VALIDATION_ERROR,
+    429: ErrorCode.RATE_LIMITED,
+    500: ErrorCode.INTERNAL_ERROR,
+    502: ErrorCode.GATEWAY_ERROR,
+    503: ErrorCode.SERVICE_UNAVAILABLE,
+}
+
+
+def create_error_response(
+    status_code: int,
+    code: str,
+    message: str,
+    trace_id: str = None,
+    details: dict = None
+) -> JSONResponse:
+    """创建统一格式的错误响应"""
+    if trace_id is None:
+        trace_id = get_trace_id()
+    
+    error_body = {
+        "code": code,
+        "message": message,
+        "trace_id": trace_id
+    }
+    
+    if details:
+        error_body["details"] = details
+    
+    return JSONResponse(
+        status_code=status_code,
+        content={"success": False, "error": error_body},
+        headers={"X-Trace-ID": trace_id}
+    )
+
+
+async def http_exception_handler(request: Request, exc: Union[HTTPException, StarletteHTTPException]):
+    """处理 HTTP 异常"""
+    trace_id = get_trace_id()
+    status_code = exc.status_code
+    error_code = STATUS_TO_ERROR_CODE.get(status_code, ErrorCode.INTERNAL_ERROR)
+    message = exc.detail if isinstance(exc.detail, str) else str(exc.detail)
+    
+    logger.warning(f"[{trace_id}] HTTP {status_code}: {message}")
+    
+    return create_error_response(
+        status_code=status_code,
+        code=error_code,
+        message=message,
+        trace_id=trace_id
+    )
+
+
+async def validation_exception_handler(request: Request, exc: RequestValidationError):
+    """处理请求验证错误"""
+    trace_id = get_trace_id()
+    errors = exc.errors()
+    error_messages = [f"{'.'.join(str(l) for l in e['loc'])}: {e['msg']}" for e in errors]
+    
+    logger.warning(f"[{trace_id}] 验证错误: {error_messages}")
+    
+    return create_error_response(
+        status_code=422,
+        code=ErrorCode.VALIDATION_ERROR,
+        message="请求参数验证失败",
+        trace_id=trace_id,
+        details={"validation_errors": error_messages}
+    )
+
+
+async def generic_exception_handler(request: Request, exc: Exception):
+    """处理所有未捕获的异常"""
+    trace_id = get_trace_id()
+    
+    logger.error(f"[{trace_id}] 未捕获异常: {type(exc).__name__}: {exc}")
+    logger.error(f"[{trace_id}] 堆栈:\n{traceback.format_exc()}")
+    
+    return create_error_response(
+        status_code=500,
+        code=ErrorCode.INTERNAL_ERROR,
+        message="服务器内部错误，请稍后重试",
+        trace_id=trace_id
+    )
+
+
+def setup_exception_handlers(app: FastAPI):
+    """配置 FastAPI 应用的异常处理器"""
+    app.add_exception_handler(HTTPException, http_exception_handler)
+    app.add_exception_handler(StarletteHTTPException, http_exception_handler)
+    app.add_exception_handler(RequestValidationError, validation_exception_handler)
+    app.add_exception_handler(Exception, generic_exception_handler)
+    
+    logger.info("异常处理器已配置")