fix(stt): add batch language routing fallback

[ComputelessComputer]

Route Char Pro multi-language batch requests through Deepgram language detection fallback when Soniox is unavailable, and allow longer Soniox async polling.

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Note

Medium Risk
Changes batch STT routing behavior by conditionally appending Deepgram as a fallback provider and alters Deepgram query generation for multi-language batches; misclassification could route traffic differently or affect transcription accuracy. Soniox polling timeout increase is low risk but may extend request lifetimes.

Overview
Improves multi-language batch transcription resiliency by appending Deepgram as a last-resort fallback in the batch provider chain when the request has multiple languages, Deepgram isn’t already selected, and the language set supports Deepgram’s language-detection mode.

Updates Deepgram batch URL generation to prefer constrained language detection (multiple detect_language=<code> params) when the requested languages are all supported for detection, instead of always using detect_language=true, with new unit/integration tests covering the en+pl case.

Extends Soniox async batch polling to up to 1 hour via configurable constants and improves the timeout error message, with a small test asserting the new limit.

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