fix: 修复系统设置的动态注入问题

- 创建 useSiteSettings composable 在应用启动时加载系统设置
- 从 window.__SITE_CONFIG__（后端注入）和 localStorage 初始化设置
- 修复 favicon 更新逻辑，正确移除旧 favicon 并添加新的
- 在路由守卫中设置页面标题，格式为 '页面名 - 网站名'
- 简化 admin.vue 和 admin-sidebar 组件，使用统一的设置管理

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/layouts/admin.vue

@@ -1,13 +1,11 @@
 <script setup lang="ts">
-import { computed, onMounted, onUnmounted } from 'vue'
+import { computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { useRouter } from 'vue-router'
 
 import AdminSidebar from '@/components/admin-sidebar/index.vue'
 import LanguageChange from '@/components/language-change.vue'
 import ToggleTheme from '@/components/toggle-theme.vue'
-import api from '@/services/api'
-import { getFileUrl } from '@/utils/config'
 
 const router = useRouter()
 const { t } = useI18n()
@@ -73,74 +71,6 @@ const breadcrumbs = computed(() => {
 
   return crumbs
 })
-
-function getAssetUrl(path: string) {
-  return getFileUrl(path)
-}
-
-function updateFavicon(favicon: string) {
-  if (!favicon)
-    return
-  const link: HTMLLinkElement = document.querySelector('link[rel*=\'icon\']') || document.createElement('link')
-  link.type = 'image/x-icon'
-  link.rel = 'shortcut icon'
-  link.href = getAssetUrl(favicon)
-  document.getElementsByTagName('head')[0].appendChild(link)
-}
-
-function updateSiteName(name: string) {
-  if (name)
-    document.title = name
-}
-
-function applySettings(settings: { site_name?: string, site_logo?: string, site_favicon?: string }) {
-  if (settings.site_favicon)
-    updateFavicon(settings.site_favicon)
-  if (settings.site_name)
-    updateSiteName(settings.site_name)
-}
-
-function handleSettingsChange(event: CustomEvent) {
-  applySettings(event.detail)
-}
-
-async function loadSystemSettings() {
-  const storedSettings = localStorage.getItem('systemSettings')
-  if (storedSettings) {
-    try {
-      applySettings(JSON.parse(storedSettings))
-    }
-    catch (e) {
-      console.error('Failed to parse systemSettings', e)
-    }
-    return
-  }
-
-  try {
-    const data = await api.get<any>('/dev/system-settings')
-    if (data) {
-      const settings = {
-        site_name: data.site_name || '',
-        site_logo: data.site_logo || '',
-        site_favicon: data.site_favicon || '',
-      }
-      localStorage.setItem('systemSettings', JSON.stringify(settings))
-      window.dispatchEvent(new CustomEvent('system-settings-changed', { detail: settings }))
-    }
-  }
-  catch (error) {
-    console.error('加载系统设置失败:', error)
-  }
-}
-
-onMounted(() => {
-  loadSystemSettings()
-  window.addEventListener('system-settings-changed', handleSettingsChange as EventListener)
-})
-
-onUnmounted(() => {
-  window.removeEventListener('system-settings-changed', handleSettingsChange as EventListener)
-})
 </script>
 
 <template>
@@ -179,4 +109,4 @@ onUnmounted(() => {
       </main>
     </UiSidebarInset>
   </UiSidebarProvider>
-</template>
+</template>