The /docs + /openapi.json title read "Douanier — the audio sub-API…" and
/healthz returned service:"douanier" — internal codename leaking to consumers.

- FastAPI title → "Nech.PL Audio Intelligence API"; description rewritten to
  describe the engines (no "customs gate" framing).
- /healthz service → "nech-audio".
- Regenerated clients/openapi.json snapshot (info.title now clean; 13 paths,
  servers=api.nech.pl/audio/v1) — feeds the generated-client pipeline (#44).

Built + redeployed; verified at the edge: openapi.json info.title and healthz
both clean. "Douanier" now survives only as the internal repo/metric name.
67 tests green.