fix: Activate Essentia service integration with correct port and logging

Commit notes

- Fixed port mismatch in env.example: Essentia is exposed on 3004 (not 3003) when running the backend locally with Essentia in Docker - Added comprehensive logging to track Essentia service availability checks - Added startup check in worker to log Essentia service status - Added Essentia status to worker health endpoint for monitoring - Enhanced hybrid analyzer logging to track analysis mode (Essentia/TypeScript) - Added Essentia section to .env.docker.example for Docker deployments

The issue was that the backend was trying to connect to localhost:3003 but docker-compose exposes Essentia on port 3004 externally (3003 internally). Now logs will clearly show whether Essentia is being used or falling back to TypeScript analysis.

Co-authored-by: armin.naimi <[email redacted]>