Merge feat/remote-builders into uconsole-cm5-incremental

Bidirectional remote building + rename uconsole-cm5 -> uConsole:
- Rename all uconsole-cm5 refs to uConsole (nixosSystem key, paths, module)
- Replace single-machine remote-builder module with multi-machine config
- Enable remote builder on lazyworkhorse -> uConsole (aarch64)
- Enable remote builder on uConsole -> lazyworkhorse (x86_64)
- Add builder system user + SSH key via agenix-rekey (secrets/builder_key.age)
- Add builder_key + gortium_password age secrets to all hosts
- Fix pre-existing bugs: missing modules in lazyworkhorse/cyt-pi,
  SSH config structure (hostKeys outside settings), cyt-pi inline user
- Remove obsolete openclaw-node service + module + age secrets

hosts/cyt-pi/configuration.nix

@@ -21,14 +21,7 @@
     settings.PermitRootLogin = "prohibit-password";
   };
 
-  # User
-  users.users.gortium = {
-    isNormalUser = true;
-    extraGroups = [ "wheel" "networkmanager" "kismet" ];
-    openssh.authorizedKeys.keys = [
-      # Populate with your public key
-    ];
-  };
+  # User (defined in users/gortium/gortium.nix)
 
   # CYT Project Dependencies (Headless)
   environment.systemPackages = with pkgs; [
@@ -77,6 +70,12 @@
     };
   };
 
+
+  # Age secrets
+  age.secrets.gortium_password = {
+    file = ../../secrets/gortium_password.age;
+  };
+
   # CYT Application Service
   systemd.services.cyt-app = {
     description = "Chasing Your Tail - Target Detector";