fix(desktop): relay host status, display, and server-side LAN candidate

- Probe relay hosts through a throwaway E2EE tunnel in the host switcher
  instead of an HTTP probe against the relay:// pseudo-URL, which always
  reported Unreachable
- Show 'via OpenChamber Relay' for relay hosts in the switcher and the
  servers list instead of the raw relay:// pseudo-URL; hide the URL-centric
  edit action for relay hosts (saving it would drop the tunnel descriptor)
- Pairing LAN candidate prefers the address the requesting client actually
  reached the server on; interface scanning could pick an unroutable virtual
  bridge (docker0), producing links whose LAN leg silently failed and forced
  devices onto the relay

packages/web/server/lib/opencode/core-routes.js

@@ -800,7 +800,7 @@ export const registerAuthAndAccessRoutes = (app, dependencies) => {
   app.get('/api/client-auth/pairing/transports', async (req, res, next) => {
     await runWithClientCreateAuth(req, res, next, async () => {
       res.setHeader('Cache-Control', 'no-store');
-      res.json(getPairingTransports());
+      res.json(getPairingTransports(req));
     });
   });