ci: try Namespace macOS

.github/workflows/test.yml

@@ -111,7 +111,7 @@ jobs:
         run: nix build .#ghostty
 
   build-macos:
-    runs-on: ghcr.io/cirruslabs/macos-ventura-xcode:latest
+    runs-on: namespace-profile-ghostty-macos
     needs: test
     env:
       # Needed for macos SDK
@@ -121,6 +121,10 @@ jobs:
         uses: actions/checkout@v4
 
       # Install Nix and use that to run our tests so our environment matches exactly.
+      - name: Setup Nix Cache
+        uses: namespacelabs/nscloud-cache-action@v1.1.0
+        with:
+          path: /nix
       - uses: cachix/install-nix-action@v24
         with:
           nix_path: nixpkgs=channel:nixos-unstable