fix(stt): pass language to groq transcription

[tianma-if]

Summary

• pass language to Groq Whisper transcription requests when configured
• prefer stt.groq.language, falling back to stt.local.language and the existing local STT language env
• add regression coverage for Groq-specific language and local fallback behavior

Fixes #55551

Tests

• .venv/bin/python -m pytest tests/tools/test_transcription_tools.py -q -k "TranscribeGroq or groq_language"
• .venv/bin/python -m ruff check tools/transcription_tools.py tests/tools/test_transcription_tools.py
• .venv/bin/python -m pytest tests/tools/test_transcription_tools.py -q
• scripts/run_tests.sh tests/tools/test_transcription_tools.py -q

[alt-glitch]

This was generated by AI during triage.

Duplicate of #55608 — same Groq STT language fix in _transcribe_groq (tools/transcription_tools.py), reading stt.groq.language > stt.local.language > the local STT env. #55608 is the earliest still-open code-only variant (canonical); #55713 was already marked a duplicate of it. Related: #55551 (the bug this fixes) and #23161 (an earlier, broader feat PR that also adds docs + a config example). Maintainer picks between the minimal code-only fix and #23161's broader version.

[tianma-if]

Closing as duplicate of #55608 per triage; the earlier PR covers the same Groq STT language config fix. Thanks.