feat(trade): implement second-hand trading/flea market feature

Add complete trade functionality including:
- TradeItem, TradeImage, TradeFavorite models with auto-migration
- TradeRepository with CRUD and favorite operations
- TradeService with business logic for listing, creating, updating, status management
- TradeHandler with RESTful endpoints for trade operations
- DTOs and converters for request/response handling

Routes include: list, get by id, create, update, delete, status update, view recording, favorite/unfavorite.

internal/wire/handler.go

@@ -34,6 +34,7 @@ var HandlerSet = wire.NewSet(
 	handler.NewVerificationHandler,
 	handler.NewAdminProfileAuditHandler,
 	handler.NewPostHandler,
+	handler.NewTradeHandler,
 
 	// 需要特殊处理的 Handler
 	ProvideUserHandler,