fix: 批量改进 (#2/#23/#38/#39/#40/#47)

- Web: 隐藏 ICP 备案号（条件渲染），联系入口改为微信咨询（条件渲染，配置 wechat 字段后生效）
- backend: 拼音回填抽取为独立 cmd/backfill-pinyin 工具，不再在启动时运行
- backend: DB 连接池参数（max_idle_conns/max_open_conns）改为配置可控，默认 10/100
- backend: Inventory 反范式字段添加注释说明快照语义
- backend: 全量 handler 采用 util.RespondSuccess/RespondCreated 统一响应格式（51 处）

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/internal/handler/warehouse.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/wangjia/jiu/backend/internal/middleware"
 	"github.com/wangjia/jiu/backend/internal/model"
+	"github.com/wangjia/jiu/backend/internal/util"
 )
 
 type WarehouseHandler struct {
@@ -22,7 +23,7 @@ func (h *WarehouseHandler) List(c *gin.Context) {
 	shopID := middleware.GetShopID(c)
 	warehouses := make([]model.Warehouse, 0)
 	h.db.Where("shop_id = ? AND deleted_at IS NULL", shopID).Find(&warehouses)
-	c.JSON(http.StatusOK, gin.H{"data": warehouses})
+	util.RespondSuccess(c, warehouses)
 }
 
 func (h *WarehouseHandler) Create(c *gin.Context) {
@@ -34,7 +35,7 @@ func (h *WarehouseHandler) Create(c *gin.Context) {
 	}
 	w.ShopID = shopID
 	h.db.Create(&w)
-	c.JSON(http.StatusCreated, gin.H{"data": w})
+	util.RespondCreated(c, w)
 }
 
 func (h *WarehouseHandler) Update(c *gin.Context) {
@@ -63,7 +64,7 @@ func (h *WarehouseHandler) Update(c *gin.Context) {
 		return
 	}
 	h.db.Where("id = ? AND shop_id = ?", w.ID, shopID).First(&w)
-	c.JSON(http.StatusOK, gin.H{"data": w})
+	util.RespondSuccess(c, w)
 }
 
 func (h *WarehouseHandler) Delete(c *gin.Context) {