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>

piper-service/Dockerfile

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+FROM python:3.11-slim
+
+RUN apt-get update && apt-get install -y \
+    libsndfile1 \
+    wget \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Download Piper voice model at build time from HuggingFace (lessac medium - good quality, fast on CPU)
+RUN mkdir -p /app/models && \
+    wget -q "https://huggingface.co/rhasspy/piper-voices/resolve/main/en/en_US/lessac/medium/en_US-lessac-medium.onnx?download=true" \
+        -O /app/models/en_US-lessac-medium.onnx && \
+    wget -q "https://huggingface.co/rhasspy/piper-voices/resolve/main/en/en_US/lessac/medium/en_US-lessac-medium.onnx.json?download=true" \
+        -O /app/models/en_US-lessac-medium.onnx.json
+
+COPY . .
+
+EXPOSE 8003
+
+HEALTHCHECK --interval=30s --timeout=10s --start-period=30s \
+    CMD python -c "import httpx; httpx.get('http://localhost:8003/health').raise_for_status()"
+
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8003", "--workers", "1"]