ci: add CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,15 @@
+name: CI
+on: [push, pull_request]
+jobs:
+  build:
+    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 test --if-present
+      - run: npm run lint --if-present
+      - run: npm run build --if-present