fix(webconfig): read the LAN address after pinning the route

startLanMode() took the caller's IP, read before the route lock. A
Wi-Fi/Ethernet switch in between left WebConfig locked to the new link
while advertising the old link's address. It now reads the selected
link's address after lockSwitching(), as startOTAUpdate() already does.

examples/simple_room_server/MyMesh.cpp

@@ -1314,8 +1314,7 @@ bool MyMesh::startWebConfig(bool force_ap, char* reply) {
     }
     _webconfig->startSetupMode(reply);
   } else if (activeNetworkLink().isConnected()) {
-    _webconfig->startLanMode(activeNetworkLink().localIP(),
-                             !mqttNetworkSetupComplete(_cli.getObserverPrefs()), reply);
+    _webconfig->startLanMode(!mqttNetworkSetupComplete(_cli.getObserverPrefs()), reply);
   } else if (!mqttNetworkSetupComplete(_cli.getObserverPrefs())) {
     _webconfig->startSetupMode(reply);
   } else {