Integrate product-ws voice demo on port 8000 alongside REST API.

Add src/voice Pipecat pipeline, browser demo at /voice-demo, and config/voice.json.

Co-authored-by: Cursor <cursoragent@cursor.com>

static/voice-demo/README.md

@@ -0,0 +1,106 @@
+# Webpage Example — Realtime Voice Chat
+
+A self-contained browser client for the engine's product websocket
+(`/ws-product`, protocol `va.ws.v1`).
+
+## Features
+
+- **Connect / Disconnect** to any `ws://` or `wss://` URL.
+- **Microphone selector + mic on/off toggle** — available input devices
+  are listed with `enumerateDevices`, and getUserMedia is requested with
+  `echoCancellation`, `noiseSuppression`, and `autoGainControl` so the
+  browser handles AEC against the bot's voice.
+- **Text composer** — type a message and press <kbd>Enter</kbd> to send
+  an `input.text` event (Shift+Enter for newline). Sending interrupts
+  any in-flight bot audio so the next reply is heard cleanly.
+- **Chat history** rendered from `input.transcript.final` (you, when
+  spoken), streamed `response.text.delta` / `response.text.final`
+  (assistant — deltas arrive ahead of the synthesized audio), and locally
+  for text you submit (the engine doesn't echo text input back as a
+  transcript).
+- **WebSocket log** panel for connection state and compact send/receive
+  events. Audio chunks are summarized so the UI does not flood.
+- **Gapless TTS playback** by scheduling each `response.audio.delta`
+  chunk back-to-back on the AudioContext.
+- **Live VU meter** + mic and bot activity indicators.
+- **Clear** button to reset history.
+
+No build step, no dependencies — just three files plus an AudioWorklet.
+
+## Layout
+
+```text
+examples/webpage/
+├── index.html
+├── styles.css
+├── app.js
+└── pcm-recorder.worklet.js
+```
+
+## Run
+
+1. Start the engine (default port `8000`):
+
+   ```bash
+   cd AI-VideoAssistant-engine-v5-pipecat-minimal
+   source .venv/bin/activate
+   export OPENAI_API_KEY=...
+   uvicorn engine.main:app --host 127.0.0.1 --port 8000
+   ```
+
+2. Open the demo page served by the same process:
+
+   ```text
+   http://127.0.0.1:8000/demo/
+   ```
+
+   The default websocket URL is derived from the page host
+   (`ws://127.0.0.1:8000/ws-product`). Click **Connect**, pick a
+   microphone if needed, click **Enable mic**, and start speaking.
+
+   Mount path and on/off are controlled in `config.json`:
+
+   ```json
+   "server": {
+     "serve_webpage": true,
+     "webpage_mount": "/demo"
+   }
+   ```
+
+   Set `"serve_webpage": false` in production if you serve the UI elsewhere.
+
+### Standalone static server (optional)
+
+You can still serve the files from another port for UI-only iteration.
+Add that origin to `server.cors_origins` in `config.json` if needed:
+
+```bash
+cd AI-VideoAssistant-engine-v5-pipecat-minimal/examples/webpage
+python -m http.server 8080
+```
+
+Then open <http://localhost:8080> and point the URL field at
+`ws://127.0.0.1:8000/ws-product`.
+
+> The browser's mic API requires a secure context. `http://localhost`
+> qualifies; if you serve from another host, use HTTPS and a `wss://`
+> URL.
+
+## Audio details
+
+- Input: mono Float32 from `getUserMedia` is resampled in the
+  AudioWorklet to PCM16 mono @ 16 kHz, framed into 20 ms chunks, and
+  sent as **binary** websocket messages (the server accepts either
+  binary or the JSON+base64 form).
+- Output: each `response.audio.delta` carries base64-encoded PCM16 @
+  16 kHz; chunks are decoded and scheduled back-to-back through Web
+  Audio. The browser handles resampling to the device rate.
+
+## Notes
+
+- Use headphones if you still hear echo despite browser AEC; the bot's
+  voice leaking back into the open mic is the most common cause of
+  feedback loops.
+- The engine's session has an inactivity timeout
+  (`session.inactivity_timeout_sec` in `config.json`). If the bot
+  doesn't respond after a long silence, reconnect.