Martin Bauer
2e0e6ad199
The background worker now runs a real librosa analyzer (tempo, beat grid, per-second energy/valence curves) instead of only the null baseline, kept behind build_analyzer() so a plain checkout without the analysis extra still runs fine. The web player reads that per-track analysis and drives a new animated "Ambience" background (bubbles, colour, current) that reacts to the beat and the mood curve as the track plays, plus a debug overlay for tuning it. Also adds a one-off script to backfill podcast cover art from iTunes.