chore: enable check-images in CI

Run check-images when charts or manifests are modified.

.github/workflows/check-images.yml

@@ -0,0 +1,27 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+name: Check Manifest Images
+on:
+  push:
+    paths:
+      - charts/**
+      - manifests/**
+
+jobs:
+  check-images:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Check manifest images
+      run: make check-images