fix(admin): 修复 Key 自动获取模型时 allowed_models 同步逻辑

- 关闭自动获取上游模型时清空 allowed_models
- 开启自动获取上游模型时立即拉取并覆盖 allowed_models
- 增加模型覆盖提示并补充相关回归测试

frontend/src/features/providers/components/KeyFormDialog.vue

@@ -276,7 +276,7 @@
               v-if="showAutoFetchWarning"
               class="text-xs text-amber-600 dark:text-amber-400"
             >
-              已配置的模型权限将在下次获取时被覆盖
+              {{ autoFetchWarningMessage }}
             </p>
           </div>
           <Switch v-model="form.auto_fetch_models" />
@@ -441,6 +441,15 @@ const showAutoFetchWarning = computed(() => {
   return true
 })
 
+const autoFetchWarningMessage = computed(() => {
+  if (!showAutoFetchWarning.value || !props.editingKey?.allowed_models) return ''
+  const models = Array.isArray(props.editingKey.allowed_models)
+    ? props.editingKey.allowed_models
+    : []
+  if (models.length === 0) return ''
+  return `当前 Key 模型权限存在以下模型：${models.map(model => `“${model}”`).join('、')}，开启自动获取后将被覆盖`
+})
+
 // 检查是否正在切换认证类型
 const switchingToVertexAI = computed(() =>
   !!props.editingKey &&
@@ -754,6 +763,7 @@ async function handleSave() {
     const authConfig = parseAuthConfig()
 
     if (props.editingKey) {
+      const shouldClearAllowedModels = !!props.editingKey.auto_fetch_models && !form.value.auto_fetch_models
       // 更新模式
       // 注意：rpm_limit 使用 null 表示自适应模式
       // undefined 表示"保持原值不变"（会在 JSON 序列化时被忽略）
@@ -769,6 +779,7 @@ async function handleSave() {
         note: form.value.note,
         is_active: form.value.is_active,
         capabilities: capabilitiesData,
+        allowed_models: shouldClearAllowedModels ? null : undefined,
         auto_fetch_models: form.value.auto_fetch_models,
         model_include_patterns: parsePatternText(form.value.model_include_patterns_text),
         model_exclude_patterns: parsePatternText(form.value.model_exclude_patterns_text)

frontend/src/features/providers/components/OAuthKeyEditDialog.vue

@@ -124,7 +124,7 @@
               v-if="showAutoFetchWarning"
               class="text-xs text-amber-600 dark:text-amber-400"
             >
-              已配置的模型权限将在下次获取时被覆盖
+              {{ autoFetchWarningMessage }}
             </p>
           </div>
           <Switch v-model="form.auto_fetch_models" />
@@ -220,6 +220,15 @@ const showAutoFetchWarning = computed(() => {
   return true
 })
 
+const autoFetchWarningMessage = computed(() => {
+  if (!showAutoFetchWarning.value || !props.editingKey?.allowed_models) return ''
+  const models = Array.isArray(props.editingKey.allowed_models)
+    ? props.editingKey.allowed_models
+    : []
+  if (models.length === 0) return ''
+  return `当前 Key 模型权限存在以下模型：${models.map(model => `“${model}”`).join('、')}，开启自动获取后将被覆盖`
+})
+
 // 表单是否可以保存
 const canSave = computed(() => {
   // 必须填写名称
@@ -345,6 +354,7 @@ async function handleSave() {
 
   saving.value = true
   try {
+    const shouldClearAllowedModels = !!props.editingKey.auto_fetch_models && !form.value.auto_fetch_models
     const updateData: EndpointAPIKeyUpdate = {
       name: form.value.name,
       internal_priority: form.value.internal_priority,
@@ -352,6 +362,7 @@ async function handleSave() {
       cache_ttl_minutes: form.value.cache_ttl_minutes,
       max_probe_interval_minutes: form.value.max_probe_interval_minutes,
       note: form.value.note,
+      allowed_models: shouldClearAllowedModels ? null : undefined,
       auto_fetch_models: form.value.auto_fetch_models,
       model_include_patterns: parsePatternText(form.value.model_include_patterns_text),
       model_exclude_patterns: parsePatternText(form.value.model_exclude_patterns_text)