feat(admin): 站点信息 + 注册开关可后台设置，模板动态渲染

新增 4 项可配置站点设置（DB持久化+内存缓存，即时生效）：
- site.brand          品牌名（页面标题/页脚/管理面板，默认 MetaLab）
- site.framework      框架名（页脚标识，默认 MetaZone）
- site.copyright_start 版权起始年（页脚，默认 2024）
- registration.enabled 注册开关（关闭后禁止新用户注册，默认 true）

实现方式：
- InjectSiteInfo 中间件：全局注入 Brand/Framework/CopyrightStart 到 gin.Context
- BuildPageData 读取 context，所有 SSR 页面自动获取站点信息
- AuthService.Register 最先检查 IsRegistrationEnabled()
- 管理后台新增「基本设置」+「注册设置」区块，文本输入手动保存 + Toggle 即时生效

internal/common/errors.go

@@ -34,4 +34,5 @@ var (
 	ErrLoginBeforeDelete    = errors.New("请先登录再注销")
 	ErrNeedsConfirmRestore  = errors.New("需要二次确认恢复账号")
 	ErrOwnerCannotDelete    = errors.New("站长不可自主注销，请先转让站长权限")
+	ErrRegistrationDisabled = errors.New("注册功能已关闭")
 )

internal/common/helper.go

@@ -6,7 +6,7 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-// BuildPageData 构建页面模板数据，自动注入登录状态与 CSRF token
+// BuildPageData 构建页面模板数据，自动注入登录状态、站点信息与 CSRF token
 func BuildPageData(c *gin.Context, extra gin.H) gin.H {
 	data := gin.H{}
 	for k, v := range extra {
@@ -20,6 +20,8 @@ func BuildPageData(c *gin.Context, extra gin.H) gin.H {
 	if token, exists := c.Get("csrf_token"); exists {
 		data["CSRFToken"] = token
 	}
+	// 注入站点信息（由 InjectSiteInfo 中间件设置）
+	injectSiteInfo(c, data)
 	return data
 }
 
@@ -48,3 +50,16 @@ func BuildAdminPageData(c *gin.Context, extra gin.H) gin.H {
 	}
 	return data
 }
+
+// injectSiteInfo 从 context 注入站点展示信息
+func injectSiteInfo(c *gin.Context, data gin.H) {
+	if brand, exists := c.Get("site_brand"); exists {
+		data["Brand"] = brand
+	}
+	if framework, exists := c.Get("site_framework"); exists {
+		data["Framework"] = framework
+	}
+	if copyrightStart, exists := c.Get("site_copyright_start"); exists {
+		data["CopyrightStart"] = copyrightStart
+	}
+}

internal/config/site_settings.go

@@ -107,3 +107,26 @@ func (s *SiteSettings) IsAuditEnabled() bool {
 func (s *SiteSettings) IsAuditTypeEnabled(auditType string, defaultVal bool) bool {
 	return s.GetBool("audit."+auditType, defaultVal)
 }
+
+// --- 站点信息设置 ---
+
+// SiteInfoDefaults 站点展示信息的默认值
+type SiteInfoDefaults struct {
+	Brand          string // 品牌名，默认 "MetaLab"
+	Framework      string // 框架名，默认 "MetaZone"
+	CopyrightStart string // 版权起始年份，默认 "2024"
+}
+
+// SiteInfo 获取站点展示信息（优先 DB 设置，fallback 默认值）
+func (s *SiteSettings) SiteInfo() SiteInfoDefaults {
+	return SiteInfoDefaults{
+		Brand:          s.Get("site.brand", "MetaLab"),
+		Framework:      s.Get("site.framework", "MetaZone"),
+		CopyrightStart: s.Get("site.copyright_start", "2024"),
+	}
+}
+
+// IsRegistrationEnabled 是否允许新用户注册
+func (s *SiteSettings) IsRegistrationEnabled() bool {
+	return s.GetBool("registration.enabled", true)
+}

internal/controller/auth_api_register.go

@@ -51,6 +51,8 @@ func (ac *AuthController) Register(c *gin.Context) {
 			common.Error(c, http.StatusConflict, "该邮箱已注册")
 		case common.ErrWeakPassword:
 			common.Error(c, http.StatusBadRequest, err.Error())
+		case common.ErrRegistrationDisabled:
+			common.Error(c, http.StatusForbidden, "注册功能已关闭")
 		default:
 			common.Error(c, http.StatusInternalServerError, "注册失败，请稍后重试")
 		}

internal/controller/auth_controller.go

@@ -23,7 +23,7 @@ func NewAuthController(authService authUseCase, tokenSvc tokenRefresher, limiter
 	return &AuthController{authService: authService, tokenService: tokenSvc, rateLimiter: limiter, cfg: cfg}
 }
 
-// RegisterPage 注册页面（已登录用户重定向到首页）
+// RegisterPage 注册页面（已登录用户重定向到首页，注册关闭时重定向到登录页）
 func (ac *AuthController) RegisterPage(c *gin.Context) {
 	if _, exists := c.Get("uid"); exists {
 		c.Redirect(http.StatusFound, "/")

internal/middleware/site_info.go

@@ -0,0 +1,19 @@
+package middleware
+
+import (
+	"metazone.cc/metalab/internal/config"
+
+	"github.com/gin-gonic/gin"
+)
+
+// InjectSiteInfo 注入站点展示信息到请求上下文（供 BuildPageData 使用）
+// 应用于引擎级全局中间件，确保所有 SSR 页面都能读取 Brand/Framework/CopyrightStart
+func InjectSiteInfo(siteSettings *config.SiteSettings) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		info := siteSettings.SiteInfo()
+		c.Set("site_brand", info.Brand)
+		c.Set("site_framework", info.Framework)
+		c.Set("site_copyright_start", info.CopyrightStart)
+		c.Next()
+	}
+}

internal/router/deps_core.go

@@ -22,14 +22,14 @@ type dependencies struct {
 	tokenCtrl       *controller.AuthController
 }
 
-func buildDepsCore(db *gorm.DB, cfg *config.Config) (
+func buildDepsCore(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings) (
 	*repository.UserRepo, *service.TokenService, *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)
+	authService := service.NewAuthService(userRepo, tokenSvc, cfg, siteSettings)
 	rateLimiter := middleware.NewRateLimiter()
 	authCtrl := controller.NewAuthController(authService, tokenSvc, rateLimiter, cfg)
 	avatarSvc := service.NewAvatarService(userRepo)

internal/router/deps_extra.go

@@ -11,7 +11,7 @@ import (
 )
 
 func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings) *dependencies {
-	userRepo, _, authService, _, authCtrl, avatarSvc, authMdw, adminController := buildDepsCore(db, cfg)
+	userRepo, _, authService, _, authCtrl, avatarSvc, authMdw, adminController := buildDepsCore(db, cfg, siteSettings)
 
 	auditRepo := repository.NewAuditRepo(db)
 	notificationRepo := repository.NewNotificationRepo(db)

internal/router/router.go

@@ -11,6 +11,7 @@ import (
 // Setup 注册所有路由
 func Setup(r *gin.Engine, db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings) {
 	r.Use(middleware.SecurityHeaders())
+	r.Use(middleware.InjectSiteInfo(siteSettings))
 
 	deps := buildDeps(db, cfg, siteSettings)
 

internal/service/auth_service.go

@@ -18,11 +18,12 @@ type AuthService struct {
 	userRepo     userAuthStore
 	tokenService tokenProvider
 	cfg          *config.Config
+	siteSettings *config.SiteSettings
 }
 
 // NewAuthService 构造函数
-func NewAuthService(userRepo userAuthStore, tokenSvc tokenProvider, cfg *config.Config) *AuthService {
-	return &AuthService{userRepo: userRepo, tokenService: tokenSvc, cfg: cfg}
+func NewAuthService(userRepo userAuthStore, tokenSvc tokenProvider, cfg *config.Config, siteSettings *config.SiteSettings) *AuthService {
+	return &AuthService{userRepo: userRepo, tokenService: tokenSvc, cfg: cfg, siteSettings: siteSettings}
 }
 
 var pwLetter = regexp.MustCompile(`[a-zA-Z]`)
@@ -56,6 +57,11 @@ func validatePassword(pw string) error {
 // rememberMe=true: refresh Cookie 持久化（30天）；false: session cookie（关浏览器即清除）
 // regIP: 注册 IP 地址
 func (s *AuthService) Register(req model.RegisterRequest, regIP string) (string, string, *model.User, error) {
+	// 0. 检查注册开关
+	if !s.siteSettings.IsRegistrationEnabled() {
+		return "", "", nil, common.ErrRegistrationDisabled
+	}
+
 	// 1. 密码强度
 	if err := validatePassword(req.Password); err != nil {
 		return "", "", nil, err