README: phone access (LAN URL, tunnel fallback, QR)

README.md

@@ -32,3 +32,27 @@ Orders persist to `server/.data/orders.json` (gitignored).
 ```sh
 cd server && npm run test:e2e   # 14 checks: order loop, auth, SSE, restart persistence
 ```
+
+## Open it on your phone
+
+Same Wi-Fi (if the network allows device-to-device):
+
+```
+http://<laptop-ip>:8787          # laptop IP from: ip -4 addr | grep 10.
+http://<laptop-ip>:8787/staff    # staff board (passcode from server/.env)
+```
+
+If the phone can't connect (some Wi-Fi networks isolate devices — this
+happens on ours), use a tunnel instead:
+
+```sh
+~/.local/bin/cloudflared tunnel --url http://localhost:8787
+# prints https://<random>.trycloudflare.com — open that on the phone
+# (URL changes on every tunnel restart)
+```
+
+Typing the long URL fails often (browser eats it as a search). QR to the rescue:
+
+```sh
+qrencode -s 12 -m 2 -o /tmp/k484-qr.png "https://<your-url>"   # then scan it
+```