feat: 从 OpenAI JWT 提取 chatgpt_plan_type 并在前端展示

OAuth 授权和 token 刷新时从 id_token 的 OpenAI auth claim 中
提取 chatgpt_plan_type（plus/team/pro/free），存入 credentials，
账号管理页面 PlatformTypeBadge 显示订阅类型。

frontend/src/components/common/PlatformTypeBadge.vue

@@ -28,6 +28,10 @@
       <Icon v-else name="key" size="xs" />
       <span>{{ typeLabel }}</span>
     </span>
+    <!-- Plan type part (optional) -->
+    <span v-if="planLabel" :class="['inline-flex items-center gap-1 px-1.5 py-1 border-l border-white/20', typeClass]">
+      <span>{{ planLabel }}</span>
+    </span>
   </div>
 </template>
 
@@ -40,6 +44,7 @@ import Icon from '@/components/icons/Icon.vue'
 interface Props {
   platform: AccountPlatform
   type: AccountType
+  planType?: string
 }
 
 const props = defineProps<Props>()
@@ -65,6 +70,24 @@ const typeLabel = computed(() => {
   }
 })
 
+const planLabel = computed(() => {
+  if (!props.planType) return ''
+  const lower = props.planType.toLowerCase()
+  switch (lower) {
+    case 'plus':
+      return 'Plus'
+    case 'team':
+      return 'Team'
+    case 'chatgptpro':
+    case 'pro':
+      return 'Pro'
+    case 'free':
+      return 'Free'
+    default:
+      return props.planType
+  }
+})
+
 const platformClass = computed(() => {
   if (props.platform === 'anthropic') {
     return 'bg-orange-100 text-orange-700 dark:bg-orange-900/30 dark:text-orange-400'

frontend/src/views/admin/AccountsView.vue

@@ -171,7 +171,7 @@
             <span v-else class="text-sm text-gray-400 dark:text-dark-500">-</span>
           </template>
           <template #cell-platform_type="{ row }">
-            <PlatformTypeBadge :platform="row.platform" :type="row.type" />
+            <PlatformTypeBadge :platform="row.platform" :type="row.type" :plan-type="row.credentials?.plan_type" />
           </template>
           <template #cell-capacity="{ row }">
             <AccountCapacityCell :account="row" />