Add snap to nix, add arm64 builders

.github/workflows/snap.yaml

@@ -8,8 +8,26 @@ on:
   workflow_dispatch: {}
 
 jobs:
-  build:
-    runs-on: ubuntu-24.04
+  build-amd64:
+    runs-on: namespace-profile-ghostty-snap
     steps:
       - uses: actions/checkout@v4
+      - name: Setup Cache
+        uses: namespacelabs/nscloud-cache-action@v1.2.0
+        with:
+          path: |
+            /nix
+            /zig
+      - uses: snapcore/action-build@v1
+
+  build-arm64:
+    runs-on: namespace-profile-ghostty-snap-arm64
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Cache
+        uses: namespacelabs/nscloud-cache-action@v1.2.0
+        with:
+          path: |
+            /nix
+            /zig
       - uses: snapcore/action-build@v1

nix/devShell.nix

@@ -14,6 +14,7 @@
   python3,
   qemu,
   scdoc,
+  snapcraft,
   valgrind,
   #, vulkan-loader # unused
   vttest,
@@ -105,6 +106,7 @@ in
         pandoc
         pkg-config
         scdoc
+        snapcraft
         zig
         zip
         zig2nix.packages.${system}.zon2nix