chore: remove ccw-litellm UI components (dead code)

The LiteLLM Python bridge was already removed (litellm-client.ts is a
stub). Remove the orphaned frontend components:
- CcwLitellmStatus component and LitellmInstallProgressOverlay
- API functions (checkCcwLitellmStatus, installCcwLitellm, uninstallCcwLitellm)
- React Query hooks (useCcwLitellmStatus, useInstallCcwLitellm, useUninstallCcwLitellm)
- Locale entries (zh/en api-settings.json ccwLitellm section)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: catlog22