feat: 实现积分与等级系统 + 签到功能 + 下拉菜单优化

- User 模型增加 exp 字段，等级规则 Lv0-Lv6
- 新增签到记录(UserCheckIn)与任务记录(UserTask)模型，唯一索引防重
- 自动签到：AuthMiddleware 验证会话后，基于 Asia/Shanghai 自然日自动签到 +5 经验
- 手动签到：下拉菜单"签到"按钮兜底，已签到显示"今日已签到"并禁用
- 首次任务经验：上传头像/设置用户名/设置个性签名各 +10，审核通过与直接更新均触发
- 经验值变动后自动比对等级，升级时通过通知系统发送"恭喜提升至 LvX"
- 下拉菜单重构：顶部头像+用户名+LvX 等级标签，菜单项增加左侧图标，优化布局样式
- 新增 API：POST /api/level/checkin、GET /api/level/info

internal/router/deps_extra.go

@@ -18,12 +18,16 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 	auditRepo := repository.NewAuditRepo(db)
 	notificationRepo := repository.NewNotificationRepo(db)
 	notificationService := service.NewNotificationService(notificationRepo)
-	auditService := service.NewAuditService(auditRepo, userRepo, siteSettings, cfg.Audit, notificationService)
+
+	// 等级/签到/任务系统
+	_, levelSvc, levelCtrl := buildDepsLevel(db, notificationService, authMdw)
+
+	auditService := service.NewAuditService(auditRepo, userRepo, siteSettings, cfg.Audit, notificationService, levelSvc)
 	auditController := adminCtrl.NewAuditController(auditService, userRepo)
 
 	messageController := controller.NewMessageController(notificationService)
 
-	settingsCtrl := controller.NewSettingsController(authService, avatarSvc, auditService, sessionMgr, cfg)
+	settingsCtrl := controller.NewSettingsController(authService, avatarSvc, auditService, sessionMgr, cfg, levelSvc)
 	siteSettingController := adminCtrl.NewSiteSettingController(
 		service.NewSiteSettingService(siteSettings),
 		&service.AuditDefaults{
@@ -49,10 +53,11 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 	return &dependencies{
 		authCtrl: authCtrl, authMdw: authMdw, maintenanceMdw: maintenanceMdw,
 		settingsCtrl: settingsCtrl,
-		messageCtrl: messageController, postCtrl: postCtrl, postService: postService, spaceCtrl: spaceCtrl,
-		studioCtrl: studioCtrl,
+		messageCtrl:  messageController, postCtrl: postCtrl, postService: postService, spaceCtrl: spaceCtrl,
+		studioCtrl:    studioCtrl,
 		adminPostCtrl: adminPostCtrl,
-		adminCtrl: adminController, auditCtrl: auditController,
+		adminCtrl:     adminController, auditCtrl: auditController,
 		siteSettingCtrl: siteSettingController,
+		levelCtrl:       levelCtrl,
 	}
 }