add github action

Author: danmar

.github/workflows/ci.yml

@@ -0,0 +1,63 @@
+name: CI
+
+on: [push]
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        node-version: [18.x, 20.x]
+
+    steps:
+    - name: Checkout code
+      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 linting
+      run: npm run lint
+
+    - name: Compile TypeScript
+      run: npm run compile
+
+    - name: Run tests
+      uses: coactions/setup-xvfb@v1
+      with:
+        run: npm test
+
+  package:
+    runs-on: ubuntu-latest
+    needs: test
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Setup Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: '20.x'
+        cache: 'npm'
+
+    - name: Install dependencies
+      run: npm ci
+
+    - name: Package extension
+      run: |
+        npm install -g @vscode/vsce
+        vsce package
+
+    - name: Upload VSIX artifact
+      uses: actions/upload-artifact@v4
+      with:
+        name: vscode-extension
+        path: '*.vsix'