Initial commit: TradeMate 外贸小助手 MVP

项目结构:
- backend/     Python FastAPI 后端
- uni-app/     uni-app跨端前端
- docs/        设计文档
- docker-compose.yml  Docker编排
- nginx/scripts/systemd 运维配置

已完成功能:
- 用户认证 (JWT)
- 智能翻译 + 回复建议
- 营销素材生成
- 客户管理 + 沉默检测
- 报价单管理
- 产品库管理
- 汇率换算
- 推送通知 (uni-push)
- WhatsApp Webhook框架
- Celery定时任务

backend/app/core/exceptions.py

@@ -0,0 +1,58 @@
+from fastapi import FastAPI, Request
+from fastapi.responses import JSONResponse
+
+
+class TradeMateException(Exception):
+    def __init__(self, code: int, message: str, detail: str = None):
+        self.code = code
+        self.message = message
+        self.detail = detail
+
+
+class NotFoundError(TradeMateException):
+    def __init__(self, resource: str = "Resource"):
+        super().__init__(404, f"{resource} not found")
+
+
+class UnauthorizedError(TradeMateException):
+    def __init__(self, detail: str = "Authentication required"):
+        super().__init__(401, "Unauthorized", detail)
+
+
+class ForbiddenError(TradeMateException):
+    def __init__(self, detail: str = "Insufficient permissions"):
+        super().__init__(403, "Forbidden", detail)
+
+
+class QuotaExceededError(TradeMateException):
+    def __init__(self, feature: str):
+        super().__init__(429, "Quota exceeded", f"Daily limit reached for {feature}. Upgrade to Pro for more.")
+
+
+class TierRestrictionError(TradeMateException):
+    def __init__(self, feature: str, required_tier: str):
+        super().__init__(
+            402,
+            "Upgrade required",
+            f"{feature} requires {required_tier} plan",
+        )
+
+
+def register_exception_handlers(app: FastAPI):
+    @app.exception_handler(TradeMateException)
+    async def handle_tradmate_exception(request: Request, exc: TradeMateException):
+        return JSONResponse(
+            status_code=exc.code,
+            content={
+                "error": exc.message,
+                "detail": exc.detail,
+                "code": exc.code,
+            },
+        )
+
+    @app.exception_handler(Exception)
+    async def handle_generic_exception(request: Request, exc: Exception):
+        return JSONResponse(
+            status_code=500,
+            content={"error": "Internal server error", "detail": str(exc) if app.debug else "An unexpected error occurred"},
+        )