ci: add GitHub Actions workflow for running tests

- Run tests on push and pull requests to master/main
- Test against Node.js 18.x, 20.x, and 22.x
- Generate coverage report on Node 20.x
- Uses npm ci for faster, reliable installs

Author: leonardomso

.github/workflows/tests.yml

@@ -0,0 +1,35 @@
+name: Tests
+
+on:
+  push:
+    branches: [master, main]
+  pull_request:
+    branches: [master, main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [18.x, 20.x, 22.x]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test
+
+      - name: Run tests with coverage
+        if: matrix.node-version == '20.x'
+        run: npm run test:coverage