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/piper_tts.py

@@ -0,0 +1,34 @@
+"""
+Piper TTS client for Pipecat pipeline.
+Calls the self-hosted Piper HTTP service.
+"""
+import io
+import logging
+import wave
+import httpx
+
+logger = logging.getLogger(__name__)
+
+
+class PiperTTSClient:
+    """HTTP client for the Piper TTS service."""
+
+    def __init__(self, base_url: str = "http://piper-tts:8003"):
+        self.base_url = base_url.rstrip("/")
+        self._client = httpx.AsyncClient(timeout=10.0)
+
+    async def synthesize(self, text: str) -> bytes:
+        """Convert text to WAV audio bytes via Piper service."""
+        try:
+            response = await self._client.post(
+                f"{self.base_url}/synthesize",
+                json={"text": text, "length_scale": 0.95, "sentence_silence": 0.15},
+            )
+            response.raise_for_status()
+            return response.content
+        except Exception as e:
+            logger.error(f"Piper TTS failed: {e}")
+            return b""
+
+    async def close(self):
+        await self._client.aclose()