magicman: add v4l2loopback virtual camera support

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hosts/magicman/configuration.nix

@@ -14,6 +14,10 @@
     "rd.udev.log_level=3"
   ];
 
+  boot.extraModprobeConfig = ''
+    options v4l2loopback exclusive_caps=1 card_label="Virtual Camera"
+  '';
+
   boot.loader.systemd-boot.configurationLimit = 3;
 
   boot.initrd.systemd.enable = true;
@@ -85,6 +89,7 @@
     wget
     curl
     git
+    v4l-utils
   ];
 
   # Do NOT change this value unless you have manually inspected all the changes it would make to your configuration,