实现租户坐席账号管理

新增 /api/staff 列表/创建/更新/禁用，按租户坐席配额校验；系统设置增加坐席账号页支持增改禁与配额展示。

server/internal/handler/router.go

@@ -16,6 +16,7 @@ func SetupRoutes(r *gin.Engine, store storage.ObjectStorage, storageCfg config.S
 	admin := NewAdminHandler()
 	channel := NewChannelHandler()
 	settings := NewSettingsHandler()
+	staff := NewStaffHandler()
 	ws := NewWsHandler()
 	widget := NewWidgetHandler()
 	upload := NewUploadHandler(store, storageCfg)
@@ -94,6 +95,13 @@ func SetupRoutes(r *gin.Engine, store storage.ObjectStorage, storageCfg config.S
 		settingsGroup.GET("", settings.Get)
 		settingsGroup.PUT("", settings.Update)
 
+		// 坐席账号（租户内）
+		staffGroup := authRequired.Group("/staff")
+		staffGroup.GET("", staff.List)
+		staffGroup.POST("", staff.Create)
+		staffGroup.PUT("/:id", staff.Update)
+		staffGroup.DELETE("/:id", staff.Delete)
+
 		// 统计
 		statistics := authRequired.Group("/statistics")
 		statistics.GET("/kpi", stats.KPIs)