Build and lint assets in CI

.github/workflows/assets.yml

@@ -0,0 +1,50 @@
+name: Assets
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+# Cancel any in-progress runs for the same branch when a new push lands.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+# Disable all permissions by default; grant minimal permissions per job.
+permissions: {}
+
+jobs:
+  build:
+    name: Build and lint assets
+
+    runs-on: ubuntu-latest
+
+    timeout-minutes: 15
+
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        with:
+          persist-credentials: false
+
+      - name: Set up Node.js
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: 'lts/*'
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Lint JavaScript
+        run: npm run lint:js
+
+      - name: Lint styles
+        run: npm run lint:css
+
+      - name: Build assets
+        run: npm run build