ci: run frontend translation check as a hard failure

Add a frontend-check-translations job that runs the new
check:frontendTranslations mage task. Like the existing
api-check-translations job, failures hard-fail CI. This makes
reviewers catch dead keys and missing $t() wiring up front instead of
having to flag them manually in pull request review.

.github/workflows/test.yml

@@ -92,6 +92,20 @@ jobs:
           chmod +x ./mage-static
           ./mage-static check:translations
 
+  frontend-check-translations:
+    runs-on: ubuntu-latest
+    needs: mage
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+      - name: Download Mage Binary
+        uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7
+        with:
+          name: mage_bin
+      - name: Check
+        run: |
+          chmod +x ./mage-static
+          ./mage-static check:frontendTranslations
+
   test-migration-smoke:
     runs-on: ubuntu-latest
     needs: