ci: build lib-vt for a variety of targets

We don't run our tests on all these targets so its not sure they all
will function correctly, but at least we can be sure they build.

.github/workflows/test.yml

@@ -15,6 +15,7 @@ jobs:
       - build-examples
       - build-flatpak
       - build-freebsd
+      - build-libghostty-vt
       - build-linux
       - build-linux-libghostty
       - build-nix
@@ -194,6 +195,48 @@ jobs:
             zig build \
             -Dsnap
 
+  build-libghostty-vt:
+    strategy:
+      matrix:
+        target:
+          [
+            aarch64-macos,
+            x86_64-macos,
+            aarch64-linux,
+            x86_64-linux,
+            x86_64-windows,
+          ]
+    runs-on: namespace-profile-ghostty-sm
+    needs: test
+    env:
+      ZIG_LOCAL_CACHE_DIR: /zig/local-cache
+      ZIG_GLOBAL_CACHE_DIR: /zig/global-cache
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+
+      - name: Setup Cache
+        uses: namespacelabs/nscloud-cache-action@a289cf5d2fcd6874376aa92f0ef7f99dc923592a # v1.2.17
+        with:
+          path: |
+            /nix
+            /zig
+
+      # Install Nix and use that to run our tests so our environment matches exactly.
+      - uses: cachix/install-nix-action@a809471b5c7c913aa67bec8f459a11a0decc3fce # v31.6.2
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
+        with:
+          name: ghostty
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+
+      - name: Build
+        run: |
+          nix develop -c zig build lib-vt \
+            -Dtarget=${{ matrix.target }} \
+            -Dsimd=false
+
   build-linux:
     strategy:
       fail-fast: false