Add garden and updates.

flake.nix

@@ -97,6 +97,22 @@
             ./hosts/hub
           ];
         };
+        garden = nixpkgs.lib.nixosSystem {
+          inherit system;
+          modules = [
+            agenix.nixosModules.default
+            {
+              environment.systemPackages = [ agenix.packages.${system}.default ];
+            }
+            (
+              { config, pkgs, ... }:
+              {
+                nixpkgs.overlays = [ overlayUnstable ];
+              }
+            )
+            ./hosts/garden
+          ];
+        };
       };
     };
 }