refactor: JWT 无状态认证替换为服务端 Session，修复记住我掉线问题

- 新增 internal/session 包：Session 结构体、Store 接口、MemoryStore（内存+后台清理）、RedisStore 预留
- Cookie 从 3 个精简为 1 个 mlb_sid（HttpOnly），移除 JWT access/refresh cookie
- 会话过期采用滑动窗口：每次请求自动续期，记住我 30 天无操作过期
- AuthMiddleware/AuthAdmin/Maintenance 中间件改用 SessionManager.Validate()
- AuthService Login/Register/ConfirmRestore 去除 token 生成，返回 *model.User
- Controller 层在登录/注册后调用 SessionManager.Create 创建会话
- AdminService UpdateUserStatus/ResetUserToken 同步销毁 session 实现即时退登
- 改密/注销时通过 DestroyByUID 删除所有 session（替换 TokenVersion 检查）
- config.yaml 新增 session 配置段（idle_timeout/remember_timeout/cleanup_interval）
- TokenService/auth_parser/auth_token 标记废弃，移除 JWT 到期字段依赖

internal/router/deps_core.go

@@ -1,12 +1,15 @@
 package router
 
 import (
+	"time"
+
 	"metazone.cc/metalab/internal/config"
 	"metazone.cc/metalab/internal/controller"
 	adminCtrl "metazone.cc/metalab/internal/controller/admin"
 	"metazone.cc/metalab/internal/middleware"
 	"metazone.cc/metalab/internal/repository"
 	"metazone.cc/metalab/internal/service"
+	"metazone.cc/metalab/internal/session"
 
 	"gorm.io/gorm"
 )
@@ -28,17 +31,26 @@ type dependencies struct {
 }
 
 func buildDepsCore(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings) (
-	*repository.UserRepo, *service.TokenService, *service.AuthService,
+	*repository.UserRepo, *session.Manager, *service.AuthService,
 	*middleware.RateLimiter, *controller.AuthController,
 	*service.AvatarService, *middleware.AuthMiddleware, *adminCtrl.AdminController,
 ) {
 	userRepo := repository.NewUserRepo(db)
-	tokenSvc := service.NewTokenService(cfg, userRepo)
-	authService := service.NewAuthService(userRepo, tokenSvc, cfg, siteSettings)
+
+	// Session 存储：内存模式（后续可切换为 RedisStore）
+	sessionStore := session.NewMemoryStore(
+		time.Duration(cfg.Session.IdleTimeout)*time.Minute,
+		time.Duration(cfg.Session.RememberTimeout)*time.Minute,
+	)
+	// 启动后台过清理 goroutine
+	sessionStore.StartCleanup(time.Duration(cfg.Session.CleanupInterval) * time.Second)
+
+	sessionMgr := session.NewManager(sessionStore, userRepo, cfg)
+	authService := service.NewAuthService(userRepo, sessionMgr, cfg, siteSettings)
 	rateLimiter := middleware.NewRateLimiter()
-	authCtrl := controller.NewAuthController(authService, tokenSvc, rateLimiter, cfg)
+	authCtrl := controller.NewAuthController(authService, sessionMgr, rateLimiter, cfg)
 	avatarSvc := service.NewAvatarService(userRepo)
-	authMdw := middleware.NewAuthMiddleware(cfg, userRepo)
-	adminController := adminCtrl.NewAdminController(service.NewAdminService(userRepo))
-	return userRepo, tokenSvc, authService, rateLimiter, authCtrl, avatarSvc, authMdw, adminController
+	authMdw := middleware.NewAuthMiddleware(cfg, sessionMgr)
+	adminController := adminCtrl.NewAdminController(service.NewAdminService(userRepo, sessionMgr))
+	return userRepo, sessionMgr, authService, rateLimiter, authCtrl, avatarSvc, authMdw, adminController
 }