Enable VS Code extension integration tests for CCA

Add setup steps to copilot-setup-steps.yml for running VS Code Extension
Host integration tests:

- Install xvfb and VS Code GUI dependencies (libasound2, libgbm1, etc.)
- Build the MCP server and bundle the extension
- Pre-download VS Code via new download:vscode script

Closes #123

Author: data-douser

.github/workflows/copilot-setup-steps.yml

@@ -60,3 +60,22 @@ jobs:
 
       - name: Copilot Setup - Install CodeQL packs used in integration tests
         run: ./server/scripts/install-packs.sh
+
+      # VS Code extension integration test prerequisites
+      - name: Copilot Setup - Install xvfb and VS Code dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y xvfb libasound2 libgbm1 libgtk-3-0 libxshmfence1
+
+      - name: Copilot Setup - Build server (extension dependency)
+        run: npm run build -w server
+
+      - name: Copilot Setup - Bundle extension and server
+        working-directory: extensions/vscode
+        run: |
+          npm run bundle
+          npm run bundle:server
+
+      - name: Copilot Setup - Download VS Code for integration tests
+        working-directory: extensions/vscode
+        run: npm run download:vscode

extensions/vscode/package.json

@@ -148,6 +148,7 @@
     "bundle": "node esbuild.config.js",
     "bundle:server": "node scripts/bundle-server.js",
     "clean": "rm -rf dist server .vscode-test/* *.vsix",
+    "download:vscode": "node scripts/download-vscode.js",
     "lint": "eslint src/ test/",
     "lint:fix": "eslint src/ test/ --fix",
     "package": "vsce package --no-dependencies --out codeql-development-mcp-server-v$(node -e 'process.stdout.write(require(`./package.json`).version)').vsix",

extensions/vscode/scripts/download-vscode.js

@@ -0,0 +1,25 @@
+#!/usr/bin/env node
+/**
+ * Downloads VS Code for integration testing.
+ *
+ * This script pre-downloads the VS Code instance required by @vscode/test-cli
+ * for running Extension Host integration tests. Used in CI/copilot setup steps
+ * to ensure VS Code is available before running tests.
+ *
+ * Usage: node scripts/download-vscode.js [version]
+ * Default version: stable
+ */
+
+import { downloadAndUnzipVSCode } from '@vscode/test-electron';
+
+const version = process.argv[2] || 'stable';
+
+console.log(`Downloading VS Code (${version}) for integration tests...`);
+
+try {
+  const vscodeExecutablePath = await downloadAndUnzipVSCode(version);
+  console.log(`✅ VS Code downloaded to: ${vscodeExecutablePath}`);
+} catch (error) {
+  console.error('❌ Failed to download VS Code:', error.message);
+  process.exit(1);
+}