- Add OpenAICustomProvider for custom OpenAI-compatible APIs
- Add ClaudeCustomProvider for custom Claude APIs
- Add configuration UI with API key and base URL inputs
- Update Providers page with all 5 provider tabs
- All providers now manageable from single page
- Add GeminiProvider with OAuth token refresh support
- Add Gemini credential management commands
- Update Providers page with tabs for Kiro/Gemini
- Auto-detect credential file changes for both providers
- Add Gemini models to /v1/models endpoint
- OAuth credentials must be set via GEMINI_OAUTH_CLIENT_ID/SECRET env vars