Add unit tests for alert-related functionality:
- alert_handler_test.go: tests for threshold CRUD operations,
alert creation with traffic_spike type, filtering, and stats
- alert_detector_test.go: tests for threshold config loading,
traffic spike severity calculation, deduplication logic,
error rate severity, and nil-safety checks
Also fix format string issues:
- Use %d instead of %.2f for integer QPS in alert messages
- Wrap error description with format directive to avoid linter warning
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
