feat: 实现关注系统 + 通知侧边栏分类 TAB + 点赞聚合通知

- 新增关注系统：UserFollow 模型、FollowService（toggle/status/列表隐私控制）
- User 新增 FollowersCount/FollowingCount/FollowListPublic/NotifyPrefs 字段
- Space 页面增加四态关注按钮（关注/已关注/回关/已互粉）+ 粉丝/关注数链接
- 新增 /space/:uid/followers 和 /space/:uid/following 列表页
- 新增 NotifyFollow/NotifyLikeAggregated 通知类型
- ReactionService 点赞时写入 daily_like_summary，访问时生成聚合通知
- FollowService 关注时触发 NotifyFollow 通知
- 消息中心侧边栏升级为分类 TAB（全部/系统通知/@艾特/点赞/关注）
- NotificationService 新增 ListByCategory 按分类分页查询

internal/router/api.go

@@ -131,4 +131,18 @@ func setupAPIRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		reactionAPI.POST("/like", d.reactionCtrl.ToggleLike)
 		reactionAPI.POST("/dislike", d.reactionCtrl.ToggleDislike)
 	}
+
+	// --- 关注 API ---
+	// 公开（未登录返回 false）
+	r.GET("/api/users/:uid/follow-status", d.followCtrl.GetStatus)
+	r.GET("/api/users/:uid/followers", d.followCtrl.Followers)
+	r.GET("/api/users/:uid/following", d.followCtrl.Following)
+	// 需登录：切换关注
+	followAPI := r.Group("/api/users/:uid")
+	followAPI.Use(d.authMdw.Required())
+	followAPI.Use(d.authMdw.BannedWriteGuard())
+	followAPI.Use(middleware.CSRF(cfg))
+	{
+		followAPI.POST("/follow", d.followCtrl.Toggle)
+	}
 }

internal/router/deps_core.go

@@ -38,6 +38,8 @@ type dependencies struct {
 	commentService  *service.CommentService
 	adminCommentCtrl *adminCtrl.AdminCommentController
 	reactionCtrl    *controller.ReactionController
+	followCtrl      *controller.FollowController
+	followPageCtrl  *controller.FollowPageController
 }
 
 func buildDepsCore(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings, redisClient *redis.Client) (

internal/router/deps_extra.go

@@ -74,6 +74,13 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 	reactionService := service.NewReactionService(db, reactionRepo)
 	reactionCtrl := controller.NewReactionController(reactionService)
 
+	// 关注系统
+	followRepo := repository.NewFollowRepo(db)
+	followService := service.NewFollowService(db, followRepo)
+	followService.SetNotifier(notificationService) // 关注通知
+	followCtrl := controller.NewFollowController(followService)
+	followPageCtrl := controller.NewFollowPageController(followService)
+
 	// 用户空间
 	spaceService := service.NewSpaceService(userRepo, postRepo)
 	spaceCtrl := controller.NewSpaceController(spaceService)
@@ -96,5 +103,7 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 		commentService:  commentService,
 		adminCommentCtrl: adminCommentCtrl,
 		reactionCtrl:    reactionCtrl,
+		followCtrl:      followCtrl,
+		followPageCtrl:  followPageCtrl,
 	}
 }

internal/router/frontend.go

@@ -45,6 +45,10 @@ func setupFrontendRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		pages.GET("/space", d.spaceCtrl.MySpace)
 		pages.GET("/space/:uid", d.spaceCtrl.ShowSpace)
 
+		// 关注/粉丝列表页
+		pages.GET("/space/:uid/followers", d.followPageCtrl.FollowersPage)
+		pages.GET("/space/:uid/following", d.followPageCtrl.FollowingPage)
+
 		// 帖子页面
 		pages.GET("/posts", d.postCtrl.ListPage)
 		pages.GET("/posts/:id", d.postCtrl.ShowPage)