Unify the StandIn calling-lane port on 9442

[alaamh]

Unifies the StandIn Microsoft Teams calling-lane (voice WebSocket) port on 9442 across the bridge.

What changed

• src/config.ts: default PORT 8080 -> 9442 (docstring updated).
• Dockerfile: EXPOSE 9442, HEALTHCHECK fallback ${PORT:-9442}.
• .env.example: PORT=9442.
• README.md, examples/basic-bridge/README.md: default port 9442; the Tailscale Funnel command now uses the path-mount form on the real route (tailscale funnel --bg --set-path /voice/msteams/stream http://127.0.0.1:9442/voice/msteams/stream) with a portless agent voice URL (wss:///voice/msteams/stream), since Funnel only serves 443/8443/10000.
• website docs (getting-started, connecting-to-standin, configuration-reference): 9442 everywhere, same Funnel fix, cloudflared/ngrok/devtunnel examples point at 9442.
• The WebSocket route path is unchanged (/voice/msteams/stream/{callId}); only the port number moved.

Version bump

• 0.1.2 -> 0.1.3 (package.json and package-lock.json), because the code default changed.

Checks run locally

• npm ci, npm run typecheck, npm test (45 pass), npm run build: PASS
• website: npm ci && npm run build: PASS