Add WebSocket broadcast to stt-server.py

Every connection receives the full event stream (vad_start, vad_end,
transcript, error) from the moment it connects — no subscription
handshake required. The asyncio WebSocket server runs in a daemon thread
alongside the VAD loop and transcription thread. Events still go to
stdout unchanged.

Port is configurable via STT_PORT env var (default: 11501).
Add websockets to both setup scripts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

setup-venv.sh

@@ -25,7 +25,7 @@ fi
 
 echo "==> installing torch and faster-whisper"
 "${VENV}/bin/pip" install --upgrade pip --quiet
-"${VENV}/bin/pip" install torch faster-whisper silero-vad
+"${VENV}/bin/pip" install torch faster-whisper silero-vad websockets
 
 echo ""
 echo "==> done. Venv ready at ${VENV}"