Add deprecation warnings to all clanModules

clanModules/admin/roles/default.nix

@@ -18,6 +18,13 @@
     ../../root-password
   ];
   config = {
+
+    warnings = [
+      "The clan.admin module is deprecated and will be removed on 2025-07-15.
+      Please migrate to user-maintained configuration or the new equivalent clan services
+      (https://docs.clan.lol/reference/clanServices)."
+    ];
+
     users.users.root.openssh.authorizedKeys.keys = builtins.attrValues config.clan.admin.allowedKeys;
   };
 }