feat(stt): add local_parakeet provider using parakeet-mlx

[caseyg]

Summary

• Adds local_parakeet as a new local STT provider using parakeet-mlx for Apple Silicon
• ~2x faster than faster-whisper with excellent English accuracy
• Auto-detected first in the fallback chain when parakeet_mlx is installed
• Follows the same singleton-model pattern as the existing local provider

Fixes #5349

Changes

• tools/transcription_tools.py — new provider detection, _transcribe_parakeet() function, dispatcher routing, auto-detect priority
• hermes_cli/config.py — add stt.parakeet.model config default

Configuration

stt:
  provider: local_parakeet  # or omit to auto-detect
  parakeet:
    model: mlx-community/parakeet-tdt-0.6b-v2

Test plan

• Install parakeet-mlx: pip install parakeet-mlx
• Set stt.provider: local_parakeet in config.yaml
• Test CLI voice mode (/voice on) — verify transcription works
• Test with provider omitted — verify auto-detection picks parakeet over whisper
• Test without parakeet-mlx installed — verify graceful fallback to local whisper
• Test gateway voice messages (Telegram/Discord) — verify transcription via gateway

🤖 Generated with Claude Code

[teknium1]

Thanks for the Apple Silicon STT contribution. This is an automated hermes-sweeper review; current main now provides this capability through the generic STT command-provider path.

• tools/transcription_tools.py:1703 resolves stt.providers.<name> command providers and dispatches them through the normal transcription pipeline.
• website/docs/user-guide/features/tts.md:491 explicitly documents Parakeet as a supported command-provider use case, including configurable provider name, model, audio input, and transcript output.
• The linked issue already has a concrete parakeet-mlx configuration workaround: feat: add parakeet-mlx as local STT provider (Apple Silicon) #5349 (comment).
• This was introduced by d3ffbc640940d8ce78ba2f5b44f0bc761e99dd45 (feat(stt): add stt.providers.<name> command-provider registry).

Closing as implemented on main.