refactor: CSP nonce替代unsafe-inline, HSTS始终启用, router/api拆分, 管理后台+用户设置页拆分, DB健康降级, 时区配置, UID统一解析, CI接入

审计修复:
- CSP: unsafe-inline移除, nonce替代; unsafe-eval保留供Vditor使用
- HSTS: 始终启用(不再依赖release模式)
- Controller Exp: common.GetGinExp包装, 不再直接读context
- UID解析: common.ParseUIDParam统一, follow/admin controller改用

重构:
- router/api.go(198行)拆为7个域文件: auth/settings/posts/comments/reactions/social/studio
- 管理后台站点设置: 单页拆为4个子页(brand/security/registration/content)+子菜单
- 前台用户设置页: 1201行拆为6个独立模板+6个独立JS文件

新增:
- DB健康检测中间件(middleware/db_health.go): 5s ping+降级页面
- 时区配置: config.yaml server.timezone→time.Local初始化
- .gitea/workflows/ci.yml: strict模式CI流水线

internal/router/admin.go

@@ -28,6 +28,14 @@ func setupAdminRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		adminPages.GET("/posts", d.adminPostCtrl.PostsPage)
 		adminPages.GET("/site-settings", d.siteSettingCtrl.SiteSettingsPage,
 			middleware.RequirePageRole(model.RoleOwner))
+		adminPages.GET("/settings/brand", d.siteSettingCtrl.BrandPage,
+			middleware.RequirePageRole(model.RoleOwner))
+		adminPages.GET("/settings/security", d.siteSettingCtrl.SecurityPage,
+			middleware.RequirePageRole(model.RoleOwner))
+		adminPages.GET("/settings/registration", d.siteSettingCtrl.RegistrationPage,
+			middleware.RequirePageRole(model.RoleOwner))
+		adminPages.GET("/settings/content", d.siteSettingCtrl.ContentPage,
+			middleware.RequirePageRole(model.RoleOwner))
 		adminPages.GET("/energy", d.adminEnergyCtrl.EnergyPage)
 		adminPages.GET("/energy/logs", d.adminEnergyCtrl.EnergyLogPage)
 		adminPages.GET("/energy/fund-logs", d.adminEnergyCtrl.FundLogPage)