hosts: add monitoring02 configuration

New test-tier host for monitoring stack expansion with:
- Static IP 10.69.13.24
- 4 CPU cores, 4GB RAM, 20GB disk
- Vault integration and NATS-based deployment enabled

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

flake.nix

@@ -191,6 +191,15 @@
             ./hosts/kanidm01
           ];
         };
+        monitoring02 = nixpkgs.lib.nixosSystem {
+          inherit system;
+          specialArgs = {
+            inherit inputs self;
+          };
+          modules = commonModules ++ [
+            ./hosts/monitoring02
+          ];
+        };
       };
       packages = forAllSystems (
         { pkgs }: