Local E2E runner

This E2E runner automates the UI flow for Broadcast Panel -> StudioPortal -> LiveKit token handshake.

Prereqs
- Node 18+
- npm packages installed in `packages/broadcast-panel` (run `npm install` there)
- Either a local Chrome launched with remote debugging or access to a remote browser service like browserless

Start local Chrome with remote debugging (example):

```bash
cd packages/broadcast-panel/e2e
chmod +x start-chrome-remote.sh
./start-chrome-remote.sh
# verify
curl http://localhost:9222/json/version
```

Run the E2E runner connecting to a remote Chrome (default) or browserless:

```bash
# Connect to local remote-debugging chrome
cd packages/broadcast-panel
node e2e/run_local_e2e.js --ws http://localhost:9222 --show

# Or connect to browserless remote (example)
REMOTE_WS="wss://browserless.bfzqqk.easypanel.host?token=e2e098863b912f6a178b68e71ec3c58d" node e2e/run_local_e2e.js --show

# To point to specific backend/broadcast hosts (useful when running remote browserless):
REMOTE_WS="..." BROADCAST_URL="https://avanzacast-broadcastpanel.bfzqqk.easypanel.host" TOKEN_SERVER="https://avanzacast-servertokens.bfzqqk.easypanel.host" node e2e/run_local_e2e.js --show
```

Notes
- The script will postMessage the LIVEKIT_TOKEN to the StudioPortal when a token is created in backend-api.
- If StudioPortal does not auto-connect, the runner will attempt to click a "Conectar" button (class .btn-small).
- Logs and screenshots are saved to `packages/broadcast-panel/e2e/out`.