router/wifi: assert no supplicant/NetworkManager owns the radios

With the AP-typed match, the station-mode netdev is unmanaged until
hostapd flips it, so any wpa_supplicant/iwd/NetworkManager in the
importing config would grab the radio first and keep resetting it to
managed mode under hostapd. Fail at eval instead of at runtime.

modules/clan/router/wifi.nix

@@ -120,6 +120,13 @@ in
         );
         message = "router: wifi.radios.<radio>.macAddress is required for radios broadcasting more than one network.";
       }
+      {
+        assertion =
+          !config.networking.wireless.enable
+          && !config.networking.wireless.iwd.enable
+          && !config.networking.networkmanager.enable;
+        message = "router: wifi.enable needs the radios for hostapd; disable networking.wireless (wpa_supplicant), iwd and NetworkManager.";
+      }
     ];
 
     # Regulatory database for the kernel, so countryCode actually applies.