Detect the language once for auto-detect file passes on the chunked path (D-053)

Transformers.js has no Whisper language detection and silently decoded
Danish as English whenever "Skip silence" was off or unavailable.

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

docs/Architecture.md

@@ -163,6 +163,9 @@ environment). See `WorkBreakdown.md` for the itemized checklist.)
    (`VocabularyHint`, stored in localStorage by `lib/hint.ts`), raw as typed (D-048).
 5. Worker runs the pipeline (chunked, with timestamps), streaming partial results
    back via `{type:"partial"}` messages; final result as `{type:"result"}`.
+   With auto-detect on a multilingual model, it first detects the language on
+   the first 30 s (`worker/language.ts`, D-053) and pins it — Transformers.js
+   itself would default to English.
    A hint becomes `<|startofprev|> hint.` once per pass (`worker/prompt.ts`,
    cut to a 120-token prompt budget at a whole word) and is prepended
    to the decoder input of every 30 s window by a wrapper around the model's