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/pages/developer/cloud-variables/[id].vue

@@ -28,7 +28,7 @@ const form = ref({
   default_value: '',
   var_type: 'string',
   scope: 'app',
-  write_permission: 'developer',
+  write_permission: 'admin',
   description: '',
   status: 'active',
 })
@@ -57,7 +57,7 @@ async function fetchVariable() {
         default_value: variable.default_value || '',
         var_type: variable.var_type || 'string',
         scope: variable.scope || 'app',
-        write_permission: variable.write_permission || 'developer',
+        write_permission: variable.write_permission || 'admin',
         description: variable.description || '',
         status: variable.status || 'active',
       }
@@ -239,10 +239,10 @@ onMounted(async () => {
               <UiRadioGroup v-model="form.write_permission" class="grid grid-cols-1 md:grid-cols-2 gap-4">
                 <div
                   class="flex items-start gap-3 p-4 rounded-lg border cursor-pointer transition-colors"
-                  :class="form.write_permission === 'developer' ? 'border-primary bg-primary/5' : 'hover:bg-accent'"
-                  @click="form.write_permission = 'developer'"
+                  :class="form.write_permission === 'admin' ? 'border-primary bg-primary/5' : 'hover:bg-accent'"
+                  @click="form.write_permission = 'admin'"
                 >
-                  <UiRadioGroupItem value="developer" class="mt-0.5" />
+                  <UiRadioGroupItem value="admin" class="mt-0.5" />
                   <div>
                     <div class="flex items-center gap-2">
                       <Icon icon="lucide:lock" class="size-4 text-primary" />
@@ -310,7 +310,7 @@ onMounted(async () => {
                 <div class="flex justify-between text-sm">
                   <span class="text-muted-foreground">{{ t('developer.cloudVariables.create.writePermission') }}</span>
                   <UiBadge variant="secondary">
-                    {{ form.write_permission === 'developer' ? t('developer.cloudVariables.create.developerOnly') : t('developer.cloudVariables.create.userWritable') }}
+                    {{ form.write_permission === 'admin' ? t('developer.cloudVariables.create.developerOnly') : t('developer.cloudVariables.create.userWritable') }}
                   </UiBadge>
                 </div>
                 <div class="flex justify-between text-sm items-center">