Katana-first finding: per-one-shot CLAP genre/mood tags are unreliable (every
hit → boom-bap/euphoric — a 0.3s sound has no genre), but the audio EMBEDDINGS
are gold for RELATIVE similarity. 'warm dusty rhodes' → suns_keys gold-keys +
west-coast electric; 'jazzy upright bass' → no_sunshine/come_bass loops; a kick's
nearest neighbours are other kicks (0.96 cross-folder). So we ship similarity,
not fake absolute labels (Principle 1: trust the instrument).

- sample_semantics.py validated on real audio; semantics_embeds.npz = 1490×512-d.
- serve.py: lazy CLAP /vibe?q= (embed any phrase → rank) + /similar?name= (by
  audio-embed cosine). 503 if unbuilt, 400/404 on bad input; static serving
  untouched. Single-user LAN, torch loads once on first hit.