fix: 修复logout清除新主题偏好; 移除DesktopLayout未使用的themeLabels导入

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/components/DesktopLayout.vue

@@ -2,7 +2,7 @@
 import { useRoute, useRouter } from 'vue-router'
 import { computed, ref } from 'vue'
 import { useAuthStore } from '@/stores/auth'
-import { useThemeStore, themeLabels } from '@/stores/theme'
+import { useThemeStore } from '@/stores/theme'
 
 const route = useRoute()
 const router = useRouter()

frontend/src/stores/auth.ts

@@ -29,10 +29,14 @@ export const useAuthStore = defineStore('auth', () => {
     userId.value = ''
     name.value = ''
     role.value = ''
-    // Preserve theme preference across logout
-    const savedTheme = localStorage.getItem('theme')
+    // Preserve theme preferences across logout
+    const savedMode = localStorage.getItem('theme-mode')
+    const savedLight = localStorage.getItem('theme-light')
+    const savedDark = localStorage.getItem('theme-dark')
     localStorage.clear()
-    if (savedTheme) localStorage.setItem('theme', savedTheme)
+    if (savedMode) localStorage.setItem('theme-mode', savedMode)
+    if (savedLight) localStorage.setItem('theme-light', savedLight)
+    if (savedDark) localStorage.setItem('theme-dark', savedDark)
   }
 
   async function casdoorLogin(code: string, state: string) {