lint CI workflow

.github/workflows/lint.yml

@@ -0,0 +1,27 @@
+name: lint
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+# Run this job for all commits to main -- even if that means multiple
+# concurrent jobs for a flurry of commits -- but only for the latest commit on
+# a PR branch.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: 'npm'
+      - run: npm ci
+      - run: npm run lint
+~