🎵 Spleeter Audio Separator - MVP (Free Tier)
    
    Endpoints:
    - POST /api/separate (upload audio file)
    - GET /api/status/<job_id> (check progress)
    - GET /api/download/<job_id>/<stem> (download result)
    - GET /api/health (server status)
    
    Limits: 5MB max file size, 1 concurrent job