Implement automatic token refresh mechanism for CPA providers (Codex,
GeminiCLI, Antigravity, ClaudeCode) with the following features:
- Periodic refresh of expiring tokens based on configurable interval
- Redis event queue processing for on-demand token refresh
- Retry logic with exponential backoff for transient failures
- Automatic key deactivation on non-retryable errors
- Provider-specific OAuth token refresh implementations
- Sync service integration to update providers after refresh
