Introduce automatic ZIP file creation and management for session-based downloads.
- Server: Add endpoints to serve and provide info about session ZIPs; VideoService now updates ZIP after each MP3 download with user-friendly filenames.
- Client: Add "Download All in ZIP" button with loading state and ZIP info; trigger browser download via JS interop; responsive and styled UI.
- API: Extend service interfaces for ZIP download/info; add SessionZipInfo model.
- Docs: Update SESSION_MANAGEMENT.md with ZIP workflow, endpoints, and UX details.
- Robust error handling and logging throughout.
Organize downloaded files into per-job subdirectories under "downloads" instead of a flat structure. Update DownloadController and VideoService to read, write, and delete files within these job-specific directories. Add helper methods for directory management and improve logging. Update download/delete endpoints and result URLs to reflect the new structure. Clean up empty job directories after file deletion.
Michal Vrba