git actions workflow for building

Author: jason-at-contrast

.github/workflows/build-vsix.yml

@@ -0,0 +1,38 @@
+name: Build VSIX on Main Merge
+
+on:
+  push:
+    branches:
+      - main
+      - feature/build-automation
+
+jobs:
+  build-vsix:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build project
+        run: npm run build
+
+      - name: Install vsce
+        run: npm install -g @vscode/vsce
+
+      - name: Package VSIX
+        run: vsce package
+
+      - name: Upload VSIX artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: contrast-vscode-plugin.vsix
+          path: '*.vsix'