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/repository.go

@@ -46,6 +46,9 @@ var RepositorySet = wire.NewSet(
 
 	// 帖子内链引用关系
 	repository.NewPostRefRepository,
+
+	// 二手交易相关
+	repository.NewTradeRepository,
 )
 
 // ProvideUserActivityRepository 提供用户活跃数据仓储