fix: 修复系统设置动态注入到静态文件

- 简化前端 useSiteSettings，直接使用后端注入的 window.__SITE_CONFIG__
- 修复后端 serveIndexHTML 中的设置 key 名，与前端的 key 名一致
- site_name 替换为正确的数据库字段名
- logo 和 favicon 使用 site_logo 和 site_favicon
- 添加 getLogo 函数根据主题自动选择 logo

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

frontend/src/components/admin-sidebar/index.vue

@@ -1,7 +1,8 @@
 <script lang="ts" setup>
-import { Boxes, Code, CreditCard, DollarSign, FileLock, Gauge, GitBranch, HardDrive, Hash, Key, KeyRound, Mail, Megaphone, MessageSquare, Monitor, Network, Plug, ScrollText, Settings, Shield, Smartphone, Users, Variable } from 'lucide-vue-next'
-import { computed, onMounted, onUnmounted, reactive, watch } from 'vue'
+import { Boxes, Code, CreditCard, DollarSign, FileLock, Gauge, GitBranch, HardDrive, Hash, Key, KeyRound, Mail, Megaphore, MessageSquare, Monitor, Network, Plug, ScrollText, Settings, Shield, Smartphone, Users, Variable } from 'lucide-vue-next'
+import { computed, onMounted, reactive, watch } from 'vue'
 import { useI18n } from 'vue-i18n'
+import { usePreferredDark } from '@vueuse/core'
 
 import NavTeam from '@/components/app-sidebar/nav-team.vue'
 import TeamSwitcher from '@/components/app-sidebar/team-switcher.vue'
@@ -9,7 +10,8 @@ import NavFooter from '@/components/admin-sidebar/nav-footer.vue'
 import { useSiteSettings } from '@/composables/use-site-settings'
 
 const { t } = useI18n()
-const { siteSettings } = useSiteSettings()
+const { siteSettings, getLogo } = useSiteSettings()
+const isDark = usePreferredDark()
 
 const user = reactive({
   name: t('nav.admin'),
@@ -20,31 +22,32 @@ const user = reactive({
 
 const teams = reactive([
   {
-    name: t('nav.adminDashboard'),
-    logo: Code as any,
+    name: '',
+    logo: '' as any,
   },
 ])
 
+// 计算当前 logo
+const currentLogo = computed(() => {
+  if (siteSettings.logoLight || siteSettings.logoDark || siteSettings.siteLogo) {
+    return getLogo(isDark.value)
+  }
+  return Code // 默认图标
+})
+
 // 监听系统设置变化
 watch(() => siteSettings.siteName, (newName) => {
   if (newName) {
     teams[0].name = newName
+  } else {
+    teams[0].name = t('nav.adminDashboard')
   }
-})
+}, { immediate: true })
 
-watch(() => siteSettings.siteLogo, (newLogo) => {
-  if (newLogo) {
-    teams[0].logo = newLogo
-  }
-})
-
-// 初始化时设置
-if (siteSettings.siteName) {
-  teams[0].name = siteSettings.siteName
-}
-if (siteSettings.siteLogo) {
-  teams[0].logo = siteSettings.siteLogo
-}
+// 监听 logo 变化
+watch(currentLogo, (newLogo) => {
+  teams[0].logo = newLogo
+}, { immediate: true })
 
 onMounted(() => {
   const storedUser = localStorage.getItem('user')
@@ -62,9 +65,6 @@ onMounted(() => {
   }
 })
 
-onUnmounted(() => {
-})
-
 const navMain = computed(() => [
   {
     title: t('nav.mainFeatures'),