STT API: clarify that words[] and utterances[] need word_timestamps=true

The STT API-ref example response showed populated words[] and utterances[] arrays, but a default request from the docs explorer or Postman returns both arrays empty (the transcription string is fine).

Both arrays are gated on the word_timestamps=true query parameter. The same flag turns on both. Without it, the API still transcribes but does not attach per-word timings or sentence-level segments.

Fixed on both endpoint schemas (/waves/v1/stt/ and legacy /waves/v1/pulse/get_text):

Response schema words and utterances descriptions now state the gate.
Example responses now carry a YAML comment naming the request shape they correspond to (word_timestamps=true, plus diarize=true where the example includes speaker).
word_timestamps query-parameter description now spells out default-off behavior and links to the Word Timestamps feature page.

Live-verified: same wav sample against both endpoints returned transcription populated with empty words[] / utterances[] when word_timestamps was omitted, and 12 words + 2 utterances when the flag was set.

TTS: opt-in math_notation flag for reading operators as words

Lightning v3.1 and v3.1_pro accept a new math_notation request field on every transport (POST /waves/v1/tts, POST /waves/v1/tts/live, and the wss://.../waves/v1/tts/live WebSocket).

Off by default. Set math_notation: true to have the normalizer read digit-flanked math operators as spoken words: 6 x 7 becomes “6 times 7”, 2 ^ 10 becomes “2 to the power of 10”, 6 ÷ 2 becomes “6 divided by 2”. The operator word follows number_pronunciation_language (Hindi and Marathi localized; every other language falls back to English).

Ambiguous glyphs (-, –, −, /) fire only when space-padded, so 5-3 still reads as a range and 1/2 still reads as a fraction. Protected patterns like ISO dates, slash dates, version strings, phone numbers, and Hindi year ranges produce identical audio whether the flag is on or off.

Full lexicon, matching rules, known limitations (product dimensions, 24x7 idiom, vehicle-reg codes), and EU-language localizations on the new Math notation page.

Hindi and Devanagari proper-noun pronunciations also improved as part of the same normalization update. No client-side change is required for that piece.