feat: provider api_formats 可空继承、OpenAI 图片 edit/variation 与用量配额多项补强

- 鉴权: provider_api_keys.api_formats 改为可空，OAuth 托管 key 自动继承 provider endpoints 激活格式，相关 handler/测试同步更新
- 图片 planner: OpenAI 图片路由新增 edit/variation 操作并完善参数校验、响应合并与流式处理
- 用量: user me usage 返回区分 client_requested_stream/upstream_is_stream，前端 usage 列表筛选与展示增强
- 统计: stats_daily_model 新增 cache_creation_ephemeral_5m/1h tokens 字段与回填链路
- 配额/observability: quota repository 新增内存与 SQL 扩展，admin observability usage 字段扩充
- 其它: OAuth 导入/轮询收敛、provider 汇总与 pool admin 读写链路小修、新增 system_config 缓存与 provider template handler

Closes #318

Co-authored-by: Entropy.Xu <[email protected]>

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

@@ -1420,21 +1420,23 @@ watch(
   [() => props.providerId, () => props.open],
   async ([newId, newOpen], [_oldId, oldOpen]) => {
     if (newOpen && newId) {
-      if (props.initialProvider?.id === newId) {
+      const hasInitialProvider = props.initialProvider?.id === newId
+      if (hasInitialProvider) {
         provider.value = props.initialProvider
         loading.value = false
       }
+      void loadSystemFormatConversionConfig()
       // mapping-preview 较慢，不阻塞首屏渲染
       void loadMappingPreview()
-      await Promise.all([
-        loadProvider(),
-        loadEndpoints(),
-      ])
+      const endpointsPromise = loadEndpoints()
+      if (!hasInitialProvider) {
+        await loadProvider()
+      }
       // 仅在抽屉刚打开时启动倒计时
       if (newOpen && !oldOpen) {
         startCountdownTimer()
       }
-      void autoRefreshQuotaInBackground()
+      void endpointsPromise.then(() => autoRefreshQuotaInBackground())
     } else if (!newOpen && oldOpen) {
       // 使在途请求失效，避免关闭后旧响应回写
       providerLoadRequestId += 1
@@ -2705,8 +2707,16 @@ async function handleKeyDrop(event: DragEvent, targetIndex: number) {
 
 // 获取密钥的 API 格式列表（按指定顺序排序）
 function getKeyApiFormats(key: EndpointAPIKey, endpoint?: ProviderEndpointWithKeys): string[] {
+  const providerType = provider.value?.provider_type
   let formats: string[] = []
-  if (key.api_formats && key.api_formats.length > 0) {
+
+  if (
+    providerType
+    && isOAuthAccountProviderType(providerType)
+    && isOAuthManagedCredential(key)
+  ) {
+    formats = [...availableKeyApiFormats.value]
+  } else if (key.api_formats && key.api_formats.length > 0) {
     formats = [...key.api_formats]
   } else if (endpoint) {
     formats = [endpoint.api_format]