feat(backend): 出入库搜索重构 + 商品编码搜索 + KPI/确认售价/详细搜索

- 搜索 keyword 命中改为 单号/酒名(名+拼音)/商品编码，去掉往来单位匹配
- applyStockOrderDetailFilters 合并明细过滤为单条子查询（同一明细语义）+ 新增 product_code
- 新增出入库 KPI summary、出库确认售价(confirm-sale) 及路由
- 补充/更新对应单元测试

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/internal/handler/testhelper_test.go

@@ -59,6 +59,7 @@ func setupProtectedRouter(db *gorm.DB) *gin.Engine {
 	// 入库路由
 	stockIn := api.Group("/stock-in")
 	stockIn.GET("/orders", stockInH.List)
+	stockIn.GET("/summary", stockInH.Summary)
 	stockIn.GET("/orders/:id", stockInH.Get)
 	stockIn.POST("/orders", stockInH.Create)
 	stockIn.PUT("/orders/:id", stockInH.Update)
@@ -72,6 +73,7 @@ func setupProtectedRouter(db *gorm.DB) *gin.Engine {
 	// 出库路由
 	stockOut := api.Group("/stock-out")
 	stockOut.GET("/orders", stockOutH.List)
+	stockOut.GET("/summary", stockOutH.Summary)
 	stockOut.GET("/orders/:id", stockOutH.Get)
 	stockOut.POST("/orders", stockOutH.Create)
 	stockOut.PUT("/orders/:id", stockOutH.Update)
@@ -80,6 +82,7 @@ func setupProtectedRouter(db *gorm.DB) *gin.Engine {
 	stockOut.PUT("/orders/:id/reject", stockOutH.Reject)
 	stockOut.PUT("/orders/:id/withdraw", stockOutH.Withdraw)
 	stockOut.POST("/orders/:id/return", stockOutH.Return)
+	stockOut.POST("/orders/:id/confirm-sale", stockOutH.ConfirmSale)
 
 	// 库存路由
 	inv := api.Group("/inventory")