Add GitHub Actions workflows for CI and npm publishing

- Add CI workflow that runs tests, type checking, and builds on push/PR
- Add publishing workflow that publishes to npm on release creation
- CI workflow tests against Node.js 18.x, 20.x, and 22.x

Author: w01fgang

.github/workflows/ci.yml

@@ -0,0 +1,36 @@
+name: CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    
+    strategy:
+      matrix:
+        node-version: [18.x, 20.x, 22.x]
+
+    steps:
+      - uses: actions/checkout@v3
+      
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: 'npm'
+      
+      - name: Install dependencies
+        run: npm ci
+      
+      - name: Type check
+        run: npx tsc --noEmit
+      
+      - name: Run tests
+        run: npm run test:run
+      
+      - name: Build
+        run: npm run build