feat: implement counter management application with drag-and-drop functionality

- Add main application component (App.tsx) to manage counters
- Create Counter component for individual counter display and editing
- Implement CreateCounter component for adding new counters
- Add API utility for handling server requests
- Set up Vite configuration with proxy for API calls
- Introduce TypeScript configuration for app and node environments
- Style application with global CSS for consistent design

frontend/vite.config.ts

@@ -0,0 +1,25 @@
+import { defineConfig } from 'vite'
+import react from '@vitejs/plugin-react'
+
+// use a fixed dev proxy target; frontend will use relative paths in production
+export default defineConfig(() => {
+  const backend = 'http://localhost:3000'
+
+  return {
+    plugins: [react()],
+    server: {
+      proxy: {
+        '/api': {
+          target: backend,
+          changeOrigin: true,
+          secure: false,
+        },
+        '/uploads': {
+          target: backend,
+          changeOrigin: true,
+          secure: false,
+        },
+      },
+    },
+  }
+})