Pulse STT

Fixed two things the Speaker diarization page and the streaming WS spec got wrong, plus tightened the page for developers rather than marketing.

speaker is an integer on both batch and streaming. The page previously claimed the batch API returned string labels (speaker_0, speaker_1, …) while streaming returned integers. Live: both return integers, zero-indexed. Example values in the docs and the response-fields table are updated. The stt-live-ws.yaml spec had speaker typed as string on the streaming word/utterance schemas; corrected to integer with example: 0 on both.

speaker_confidence appears on batch too. The table previously claimed the field was streaming-only. Live: batch responses also include speaker_confidence (0.0–1.0) on words[]. Corrected.

Interim streaming events do not carry words[]. New section clarifies that speaker attribution appears only on is_final: true transcription events. Live captions that rely on interim events should hold the speaker from the last final event and update on the next one.

Pulse Pro carve-out. ?model=pulse-pro&diarize=true returns a transcript-only response with no speaker fields and no utterances[]. Now documented explicitly on the page.

Every claim on the page is verified against live production. Reproduce with python3 scripts/spec-live-tests/diarization_live_test.py (new); 16/16 checks pass.