First draft: add CI

.github/workflows/ci.yml

@@ -0,0 +1,20 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Setup Node
+        uses: actions/setup-node@v3
+        with:
+          node-version: "18"
+      - name: Install dependencies
+        run: npm ci
+      - name: Build
+        run: npm run build