feat: initial commit — VoiceCoach real-time voice coaching pipeline

Services: Pipecat agent (LiveKit + Claude + Whisper STT + Piper TTS),
SpeechBrain analysis service, Piper TTS service, web client (nginx).
Includes LiveKit server config and docker-compose orchestration.

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

pipecat-agent/Dockerfile

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+FROM python:3.11-slim
+
+RUN apt-get update && apt-get install -y \
+    libsndfile1 \
+    ffmpeg \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Pre-download faster-whisper medium model at build time
+RUN python -c "\
+from faster_whisper import WhisperModel; \
+WhisperModel('medium', device='cpu', compute_type='int8'); \
+print('Whisper model downloaded.')"
+
+COPY . .
+
+HEALTHCHECK --interval=30s --timeout=10s --start-period=30s \
+    CMD python -c "print('pipeline process alive')" || exit 1
+
+CMD ["python", "main.py"]