refactor(auth): replace dashboard sessions with stateless tokens and session control (#6329)

* refactor(auth): replace dashboard sessions with stateless tokens

* feat(auth): harden session issuance and distributed enforcement

* fix(proxy): preserve trusted proxy compatibility defaults

* refactor: address dashboard auth review feedback

* refactor: remove classic frontend and flatten web app

setting/system_setting/theme.go

@@ -1,32 +0,0 @@
-package system_setting
-
-import (
-	"github.com/QuantumNous/new-api/common"
-	"github.com/QuantumNous/new-api/setting/config"
-)
-
-type ThemeSettings struct {
-	Frontend string `json:"frontend"`
-}
-
-var themeSettings = ThemeSettings{
-	Frontend: "classic",
-}
-
-func init() {
-	config.GlobalConfig.Register("theme", &themeSettings)
-	syncThemeToCommon()
-}
-
-func syncThemeToCommon() {
-	common.SetTheme(themeSettings.Frontend)
-}
-
-func GetThemeSettings() *ThemeSettings {
-	return &themeSettings
-}
-
-// UpdateAndSyncTheme syncs the theme config to common after DB load.
-func UpdateAndSyncTheme() {
-	syncThemeToCommon()
-}