ci: add check that ensures POT files are up to date

.github/workflows/test.yml

@@ -25,6 +25,7 @@ jobs:
       - prettier
       - alejandra
       - typos
+      - translations
       - test-pkg-linux
       - test-debian-12
     steps:
@@ -593,6 +594,42 @@ jobs:
       - name: typos check
         run: nix develop -c typos
 
+  translations:
+    if: github.repository == 'ghostty-org/ghostty'
+    runs-on: namespace-profile-ghostty-sm
+    timeout-minutes: 60
+    env:
+      ZIG_LOCAL_CACHE_DIR: /zig/local-cache
+      ZIG_GLOBAL_CACHE_DIR: /zig/global-cache
+    steps:
+      - uses: actions/checkout@v4 # Check out repo so we can lint it
+      - name: Setup Cache
+        uses: namespacelabs/nscloud-cache-action@v1.2.0
+        with:
+          path: |
+            /nix
+            /zig
+      - uses: cachix/install-nix-action@v30
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - uses: cachix/cachix-action@v15
+        with:
+          name: ghostty
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+          skipPush: true
+          useDaemon: false # sometimes fails on short jobs
+      - name: check translations
+        run: |
+          old_pot=$(mktemp)
+          cp po/com.mitchellh.ghostty.pot "$old_pot"
+          nix develop -c zig build update-translations
+
+          # Compare previous POT to current POT
+          msgcmp "$old_pot" po/com.mitchellh.ghostty.pot --use-untranslated
+
+          # Compare all other POs to current POT
+          for f in po/*.po; do msgcmp "$f" po/com.mitchellh.ghostty.pot; done
+
   test-pkg-linux:
     strategy:
       fail-fast: false