- Add Health, Video, and Download controllers with endpoints for health checks, video details, processing, status, results, and simulated downloads
- Implement IVideoService for YouTube URL validation and mock video info
- Add API models for responses and job status tracking
- Configure DI, CORS (BlazorPolicy), OpenAPI, and root metadata endpoint in Program.cs
- Add README with usage, troubleshooting, and development notes
- Minor project file cleanup and encoding fix
