统一角色体系为admin/agent/user，修复代理查询角色错误，添加语言切换和明暗切换

frontend/src/layouts/agent.vue

@@ -6,7 +6,9 @@ import { useRouter } from 'vue-router'
 
 import NavTeam from '@/components/app-sidebar/nav-team.vue'
 import TeamSwitcher from '@/components/app-sidebar/team-switcher.vue'
+import LanguageChange from '@/components/language-change.vue'
 import ThemePopover from '@/components/custom-theme/theme-popover.vue'
+import ToggleTheme from '@/components/toggle-theme.vue'
 
 const router = useRouter()
 
@@ -218,7 +220,9 @@ function handleLogout() {
             </template>
           </UiBreadcrumbList>
         </UiBreadcrumb>
-        <div class="ml-auto">
+        <div class="ml-auto flex items-center gap-2">
+          <LanguageChange />
+          <ToggleTheme />
           <ThemePopover />
         </div>
       </header>

frontend/src/layouts/developer.vue

@@ -3,7 +3,9 @@ import { computed } from 'vue'
 import { useRouter } from 'vue-router'
 
 import DeveloperSidebar from '@/components/developer-sidebar/index.vue'
+import LanguageChange from '@/components/language-change.vue'
 import ThemePopover from '@/components/custom-theme/theme-popover.vue'
+import ToggleTheme from '@/components/toggle-theme.vue'
 
 const router = useRouter()
 
@@ -91,6 +93,8 @@ const breadcrumbs = computed(() => {
         </UiBreadcrumb>
 
         <div class="ml-auto flex items-center gap-2">
+          <LanguageChange />
+          <ToggleTheme />
           <ThemePopover />
         </div>
       </header>