fix(webv2): audio uploads as Ref2VA references

[lstein]

What

Follow-ups to the audio-upload ingest from #195, in the Ref2VA reference list:

1. A reference made from an uploaded audio file starts on "Audio only" instead of "Video + audio" — it was conditioning the generation on a picture of the sound as well as the sound.
2. The add button is now "Add video or audio", and its file picker offers the accepted media extensions explicitly.
3. Windows Media (.wmv/.asf/.wma) uploads are accepted.
4. CI: the frontend-webv2-tests job's timeout-minutes raised from 10 to 20.

How

Audio-only default. The ingest route already stamps media_origin: audio_upload on wrapped audio uploads. getDefaultReferenceConditioning(metadata) reads that stamp, and VideoReferenceListField fetches the clip's metadata in parallel with the gallery resolve, so the add costs no extra round trip; a failed fetch falls back to the ordinary video default. Reading the server's stamp rather than the picked file's MIME type also covers a clip uploaded through the gallery first and then dragged onto the reference list. Recall (which restores the recorded conditioning) and the reference-extend anchor are untouched.

One button, not two. An uploaded audio file becomes a waveform video, so it fills a video reference slot and shares that cap. Two buttons would show the same counter and grey out together — "Add audio (3/3)" disabled because you added three videos — so the single button is relabeled instead. The picker keeps the video/* and audio/* wildcards and adds the extension list: a file whose type the OS cannot map arrives as application/octet-stream, and then only the extension matches.

Windows Media. Verified against the bundled ffmpeg (v7.0.2, which demuxes ASF and decodes wmv1/2/3, VC-1, wmav1/2/pro): a .wmv fixture transcodes to H.264/AAC and a .wma fixture wraps into a waveform clip. .wmv/.asf/.wma added to the upload route's extension lists and to the gallery's client-side classifier so the two agree.

CI timeout. check:architecture is lint + the unit/browser/fixture suites + a production build + the performance and project-file gates — ~9-10 minutes against a 10-minute cap (recent runs: 571s, 585s, 594s, 597s), so slightly slow runners cancelled healthy runs; two were cancelled on this branch and one on an unrelated PR. Happy to split this commit into its own PR if you'd rather.

Testing

• getDefaultReferenceConditioning unit tests (stamped / unstamped / absent metadata).
• _classify_upload parametrized tests for the octet-stream extension fallback (.wmv, .asf, .wma, .MOV, .M4A, rejection of .txt); classifyGalleryUpload rows for .wmv/.WMA.
• pytest tests/app/routers/test_videos_multiuser.py — 66 passed.
• pnpm run check:architecture green locally (509 unit + 158 browser files, perf and project-file gates included).

🤖 Generated with Claude Code

https://claude.ai/code/session_01S4B5exWsbC2z2Uu2tA167A