feat: add CI workflow for pull request validation

- Runs on pull requests and main branch pushes
- Tests across Node.js versions 18, 20, and 22
- Validates code with tests, coverage, linting, and benchmarks
- Ensures quality before merging

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: efouts

.github/workflows/ci.yml

@@ -0,0 +1,42 @@
+name: CI
+
+on:
+  pull_request:
+    branches: [ main ]
+  push:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [18, 20, 22]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v2
+        with:
+          version: latest
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Run tests
+        run: pnpm test
+
+      - name: Run tests with coverage
+        run: pnpm run test:coverage
+
+      - name: Run linting
+        run: pnpm run lint
+
+      - name: Run benchmarks
+        run: pnpm run benchmark