Companion app pairing

Experimental. The System screen shows a one-time pairing code as a QR code. A paired phone gets its own device token. Only the hash is stored on the server.

• The code lives five minutes and is only shown on a panel in the LAN, so showing it proves presence.
• A device token replaces the browser-origin check for that device and is required over remote access.
• Someone who opened Hauser in the phone’s browser gets Open in the app on this device instead of a code to scan.

The companion app itself is a separate project and not part of the Hauser release.