fix(stt): better error logging and smarter DM when STT lazy-install fails

[damiankluk]

Problem

When a user sends a voice message and faster-whisper is not installed, the gateway:

1. Attempts a lazy-install via uv pip install
2. If it fails (common reason: venv owned by different UID), logs the error at DEBUG level only — invisible to operators
3. Sends a generic DM telling the user to set stt.enabled: true even when it is already true
4. The agent gets a note saying "no STT provider is configured" with no context about why

Changes

tools/transcription_tools.py

• _try_lazy_install_stt(): Log failures at WARNING instead of DEBUG, with the actual exception message and actionable guidance for the most common cause — the Hermes process user cannot write to the virtual environment (UID mismatch in Docker/user-namespace setups).

gateway/run.py — STT failure DM (sent to user)

• The DM now reads the actual stt config before composing advice:
  • If stt.enabled: false → says so specifically
  • If stt.provider: local or auto-detected → shows a permission-aware install command
  • For cloud providers → suggests checking the API key
  • Falls back to the original generic message if anything fails

gateway/run.py — Agent context note

• The agent-facing note now includes a config-aware hint about WHY transcription failed (e.g. "provider is local but faster-whisper failed to install — likely a venv write-permission issue") so the agent can give better responses.

Root cause investigated

In the reporters environment (Docker with user-namespace mapping), the gateway process runs as uid=1000 but the Hermes venv (/opt/hermes/.venv/) is owned by uid=10000. All lazy-installs fail silently because uv pip install cannot write to the venv. The .env file now includes PYTHONPATH=/home/hermes/.hermes/venv_ext pointing to a writable extension directory where faster-whisper has been pre-installed.

Testing

• Verified that faster-whisper == 1.2.1 works when PYTHONPATH includes the extension directory
• Transcribed a real Polish voice message successfully
• All existing tests pass

[tonydwb]

Code Review Summary

Verdict: Approved

Improves STT lazy-install failure logging and adds smarter DM message when STT fails to install.

Looks Good

• Better error context for debugging STT installation failures.
• Cleaner user-facing messaging for install failures.
• Well-scoped change.

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Reviewed by Hermes Agent