Introduce OAuthRefreshAPI as the single entry point for all OAuth token
refresh operations, eliminating the race condition where background
refresh and inline refresh could simultaneously use the same
refresh_token (fixes#1035).
Key changes:
- Add OAuthRefreshExecutor interface extending TokenRefresher with CacheKey
- Add OAuthRefreshAPI.RefreshIfNeeded with lock → DB re-read → double-check flow
- Add ProviderRefreshPolicy / BackgroundRefreshPolicy strategy types
- Simplify all 4 TokenProviders to delegate to OAuthRefreshAPI
- Rewrite TokenRefreshService.refreshWithRetry to use unified API path
- Add MergeCredentials and BuildClaudeAccountCredentials helpers
- Add 40 unit tests covering all new and modified code paths
- 新增并接通 Sora 专用 OAuth 接口与 ST/RT 换取能力
- 完成前端 Sora 授权、RT/ST 手动导入与账号创建流程
- 强化 Sora token 恢复、转发日志与网关路由隔离行为
- 补充后端服务层与路由层相关测试覆盖
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
