feat(oauth): 允许替换已失效的活跃 OAuth 账号并同步 status_snapshot

- 活跃但 token 已过期或刷新失败的重复账号视为可替换
- 清除失效标记、刷新配额时同步更新 status_snapshot.oauth
- oauth_invalid 清除接口同时识别 invalid_at 与 invalid_reason 两种标记
- 批量导入任务状态区分 created_count / replaced_count，前端据此展示新增/替换统计
- 补充重复替换场景的集成测试，用量测试等待超时从 10s 提升到 30s 以适应并行压力

frontend/src/api/endpoints/provider_oauth.ts

@@ -28,6 +28,7 @@ export interface ProviderOAuthCompleteResponseWithKey {
   expires_at?: number | null
   has_refresh_token: boolean
   email?: string | null
+  replaced?: boolean
 }
 
 export interface OAuthBatchImportResultItem {
@@ -49,6 +50,8 @@ export interface OAuthBatchImportTaskStartResponse {
   processed: number
   success: number
   failed: number
+  created_count?: number
+  replaced_count?: number
   progress_percent: number
   message?: string | null
 }
@@ -62,6 +65,8 @@ export interface OAuthBatchImportTaskStatusResponse {
   processed: number
   success: number
   failed: number
+  created_count?: number
+  replaced_count?: number
   progress_percent: number
   message?: string | null
   error?: string | null