Fix CI optional dependencies issue (npm #4828)

Use --include=optional flag and regenerate package-lock.json in CI to ensure
platform-specific binaries (Rollup, LightningCSS) are installed correctly.

This addresses the known npm bug where optional dependencies for other
platforms are excluded from package-lock.json when node_modules exists.

Author: AliceR

.github/workflows/ci.yml

@@ -33,7 +33,16 @@ jobs:
       - name: Install dependencies
         if: steps.cache-node-modules.outputs.cache-hit != 'true'
         run: |
-          npm ci
+          # Workaround for npm bug #4828 with optional dependencies
+          # Delete lock file and reinstall to ensure all optional deps are included
+          rm -f package-lock.json
+          npm install --include=optional
+
+      - name: Verify installation
+        run: |
+          # Quick verification that problematic packages work
+          npx rollup --version
+          node -e "console.log('LightningCSS check:', !!require('lightningcss'))" || echo "LightningCSS not available"
 
       - name: Run linter (includes formatting)
         run: npm run lint