ci: add typecheck, test, and build workflow on Node 18/20/22

Author: ronnyabuto

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  ci:
+    name: typecheck / test / build (Node ${{ matrix.node-version }})
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [18, 20, 22]
+      # Don't cancel the whole matrix if one version fails — see all failures at once
+      fail-fast: false
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Type check
+        run: npm run typecheck
+
+      - name: Test
+        run: npm test
+
+      - name: Build
+        run: npm run build