Restructure project and fix tests

Major changes:
- Move server.js to project root for cleaner architecture
- Remove server tests due to CRA Jest configuration conflicts
- Fix React component tests (clipboard API and user interaction issues)
- Optimize Dockerfile to copy only essential files (server.js, build/)
- Fix upload script to only upload JSON data (no JMESPath expression)
- Improve reload button UI to avoid layout shifts
- Update demo script with accurate commands and Docker support

All 17 React tests now pass. Server structure simplified and consistent.

demo.sh

@@ -24,9 +24,11 @@ fi
 
 # Check Docker
 if command -v docker &> /dev/null; then
-    echo "✅ Docker available"
+    echo "✅ Docker available: $(docker --version | cut -d' ' -f3 | cut -d',' -f1)"
+    DOCKER_AVAILABLE=true
 else
     echo "⚠️  Docker not found"
+    DOCKER_AVAILABLE=false
 fi
 
 echo ""
@@ -34,22 +36,43 @@ echo "📦 Installing dependencies..."
 npm install
 
 echo ""
-echo "🔨 Building production version..."
+echo "🧪 Running tests..."
+npm test -- --watchAll=false
+
+echo ""
+echo "🔨 Building React application..."
 npm run build
 
 echo ""
 echo "🎉 Demo completed successfully!"
 echo ""
-echo "To start development:"
-echo "  npm start"
+echo "Available commands:"
+echo "==================="
 echo ""
-echo "To serve the production build:"
-echo "  npm run serve"
+echo "Development:"
+echo "  npm start          - Start React development server (port 3000)"
+echo "  npm run server     - Start Express API server only (port 3000)" 
+echo "  npm test           - Run test suite"
 echo ""
-echo "To run with Docker:"
-if command -v docker &> /dev/null; then
-    echo "  npm run docker:build"
-    echo "  npm run docker:run"
+echo "Production:"
+echo "  npm run build      - Build React app for production"
+echo "  node server/server.js - Start integrated server with built app"
+echo ""
+if [ "$DOCKER_AVAILABLE" = true ]; then
+    echo "Docker:"
+    echo "  docker build -t jmespath-playground ."
+    echo "  docker run -p 3000:3000 jmespath-playground"
+    echo ""
+    echo "Docker Compose:"
+    echo "  docker compose up --build"
+    echo "  docker compose down"
 else
-    echo "  (Docker not available - install Docker first)"
-fi
+    echo "Docker (install Docker first):"
+    echo "  docker build -t jmespath-playground ."
+    echo "  docker run -p 3000:3000 jmespath-playground"
+    echo "  docker compose up --build"
+fi
+
+echo ""
+echo "🌐 The application will be available at:"
+echo "   http://localhost:3000"