### The int_codec model and vectors: trained and coded on a generated signal

- The int_codec model and vectors are now trained and coded on a generated signal;
  earlier revisions used a third-party recording.
- `tools/wai_int_audio_export.py` reads no audio file. It writes its training signal
  and the clip it codes from a seed (16 kHz mono: tones, chirps, noise bursts and
  speech-like formant sweeps), in integer arithmetic, so a seed gives the same samples
  on every machine; `--signal-only` writes one with the Python standard library alone.
  Training is seeded from the same seed with deterministic algorithms and a fixed
  thread count: two runs gave byte-identical files. The seed and the command are in
  [`wai-rs/tests/vectors/int_audio/README.md`](wai-rs/tests/vectors/int_audio/README.md).
- Regenerated through their generators: `wai-rs/tests/vectors/int_audio/` (the model,
  both bitstream forms, `audio.json`, `sha256.json`); `int-payload-conformance`'s
  `vectors.json` and its thirteen `wia1_*` refusal fixtures; the staged-delivery case
  `audio_int_codec_1l` and `index.json`; the staged-measurement audio title,
  `goldens.json` and `sim/results.json`. The `WIA1` format, the capability and the
  model's shape are unchanged. `wai_int_payload_vectors` now reads the place of a
  `WIA1`'s first table from the payload's header for the two fixtures that change it, so
  they keep their meaning on tables of another length (on the earlier vector the
  offsets are the same).
- `tools/wai_audio_provenance_check.py`, run by CI: every committed audio vector is read
  to PCM and correlated, at every lag, with the reference recordings the CI host has;
  above 0.5 it fails, and a host with none skips it and says so.
- Every corpus states its content's provenance: a `**Provenance.**` line in each
  `*-conformance/README.md` (OER/2's settled corpus aside) and a row per directory in
  `wai-rs/tests/vectors/README.md`, required by `tests/corpus_provenance.rs`.
  CONTRIBUTING states the rule. Two vectors are flagged there as not generated and to
  be replaced: `int_video`'s `video_real` and `neural-conformance`'s `photo`.

