feat: upgrade to React 19, add keyboard shortcuts, implement Zustand global state, fix environment variables, and improve UI components

- Upgrade React to v19.1.1 and update all related packages
- Add comprehensive keyboard shortcuts (Space, R, S, Ctrl+D) with visual indicators
- Implement Zustand global state management for shortcuts and app state
- Fix .env file loading with dotenv package and proper Vite configuration
- Add text wrapping to all card components to prevent overflow
- Improve theme toggle visibility and styling in sidebar
- Update button layouts to use flex-direction: row
- Add hover effects and consistent styling across components
- Fix infinite loop issues in keyboard shortcuts hook
- Update Vite config to properly handle .env files and source directories
- Add proper TypeScript configuration for React 19 JSX transform

client/src/pages/not-found.tsx

@@ -8,7 +8,9 @@ export default function NotFound() {
         <CardContent className="pt-6">
           <div className="flex mb-4 gap-2">
             <AlertCircle className="h-8 w-8 text-red-500" />
-            <h1 className="text-2xl font-bold text-gray-900">404 Page Not Found</h1>
+            <h1 className="text-2xl font-bold text-gray-900">
+              404 Page Not Found
+            </h1>
           </div>
 
           <p className="mt-4 text-sm text-gray-600">