Offer Whisper's Translate to English only on models trained for it (canTranslate)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/Architecture.md

@@ -141,7 +141,7 @@ environment). See `WorkBreakdown.md` for the itemized checklist.)
    `AudioContext.decodeAudioData`, downmixes to mono, resamples to 16 kHz,
    transfers the `Float32Array` to the worker. For multilingual models the
    `transcribe` message also carries `language` (or auto-detect) and `task`
-   (transcribe | translate).
+   (transcribe | translate — translate only for models with `canTranslate`, D-WS4a).
 5. Worker runs the pipeline (chunked, with timestamps), streaming partial results
    back via `{type:"partial"}` messages; final result as `{type:"result"}`.