新增客户标签库：管理员维护、员工选择

租户级标签 CRUD 与颜色预设；客户打标仅能从库中选择，设置页提供管理入口，列表筛选随标签库动态生成。

server/internal/handler/router.go

@@ -11,6 +11,7 @@ func SetupRoutes(r *gin.Engine, store storage.ObjectStorage, storageCfg config.S
 	auth := NewAuthHandler()
 	session := NewSessionHandler()
 	customer := NewCustomerHandler()
+	customerTag := NewCustomerTagHandler()
 	knowledge := NewKnowledgeHandler()
 	quickReply := NewQuickReplyHandler()
 	stats := NewStatisticsHandler()
@@ -77,6 +78,13 @@ func SetupRoutes(r *gin.Engine, store storage.ObjectStorage, storageCfg config.S
 		customers.PUT("/:id", customer.Update)
 		customers.DELETE("/:id", customer.Delete)
 
+		// 客户标签库（管理员维护，全员可读可选）
+		ctags := authRequired.Group("/customer-tags")
+		ctags.GET("", customerTag.List)
+		ctags.POST("", customerTag.Create)
+		ctags.PUT("/:id", customerTag.Update)
+		ctags.DELETE("/:id", customerTag.Delete)
+
 		// 知识库
 		kb := authRequired.Group("/knowledge")
 		kb.GET("/categories", knowledge.ListCategories)