feat: add hook system, QR code login, and layered cache

- Implement extensible hook system for content moderation with
  builtin and AI-powered moderation hooks
- Add QR code login feature with SSE for real-time status updates
  and scan/confirm/cancel workflow
- Introduce layered cache with local LRU + Redis backend for
  improved read performance
- Refactor post and comment services to use hook-based moderation
  instead of direct AI service calls
- Add local cache configuration options (size, buckets, ttl)

internal/router/router.go

@@ -32,6 +32,7 @@ type Router struct {
 	adminGroupHandler     *handler.AdminGroupHandler
 	adminDashboardHandler *handler.AdminDashboardHandler
 	adminLogHandler       *handler.AdminLogHandler
+	qrcodeHandler         *handler.QRCodeHandler
 	logService            *service.LogService
 	jwtService            *service.JWTService
 	casbinService         service.CasbinService
@@ -60,6 +61,7 @@ func New(
 	adminGroupHandler *handler.AdminGroupHandler,
 	adminDashboardHandler *handler.AdminDashboardHandler,
 	adminLogHandler *handler.AdminLogHandler,
+	qrcodeHandler *handler.QRCodeHandler,
 	logService *service.LogService,
 	activityService service.UserActivityService,
 	casbinService service.CasbinService,
@@ -91,6 +93,7 @@ func New(
 		adminGroupHandler:     adminGroupHandler,
 		adminDashboardHandler: adminDashboardHandler,
 		adminLogHandler:       adminLogHandler,
+		qrcodeHandler:         qrcodeHandler,
 		logService:            logService,
 		jwtService:            jwtService,
 		casbinService:         casbinService,
@@ -183,6 +186,24 @@ func (r *Router) setupRoutes() {
 			users.GET("/:id/favorites", middleware.OptionalAuth(r.jwtService), r.postHandler.GetFavorites)
 		}
 
+		// 二维码登录（公开）
+		if r.qrcodeHandler != nil {
+			qrcode := v1.Group("/auth/qrcode")
+			{
+				qrcode.GET("", r.qrcodeHandler.GetQRCode)
+				qrcode.GET("/events", r.qrcodeHandler.SSEEvents)
+			}
+
+			// 二维码操作（需认证）
+			qrcodeAuth := v1.Group("/auth/qrcode")
+			qrcodeAuth.Use(authMiddleware)
+			{
+				qrcodeAuth.POST("/scan", r.qrcodeHandler.Scan)
+				qrcodeAuth.POST("/confirm", r.qrcodeHandler.Confirm)
+				qrcodeAuth.POST("/cancel", r.qrcodeHandler.Cancel)
+			}
+		}
+
 		// 认证路由（公开）
 		authPublic := v1.Group("/auth")
 		{