Migrate from Create React App to Vite

CRA (react-scripts 5.0.1) is abandoned and incompatible with TypeScript 5.x.
Vite provides faster builds, active maintenance, and native TS5 support.

- Replace react-scripts with vite + @vitejs/plugin-react
- Move index.html to root with script module entry point
- Replace setupProxy.js with vite.config.ts proxy config
- Rename env vars from REACT_APP_ to VITE_ prefix
- Update tsconfig for bundler module resolution
- Add nginx setup script for deployment

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -2,7 +2,6 @@
   "name": "hihala-dashboard",
   "version": "0.1.0",
   "private": true,
-  "proxy": "http://localhost:8090",
   "dependencies": {
     "@testing-library/dom": "^10.4.1",
     "@testing-library/jest-dom": "^6.9.1",
@@ -16,38 +15,20 @@
     "react-chartjs-2": "^5.3.1",
     "react-dom": "^19.2.4",
     "react-router-dom": "^7.13.0",
-    "react-scripts": "5.0.1",
     "web-vitals": "^2.1.4"
   },
   "scripts": {
-    "start": "react-scripts start",
-    "build": "react-scripts build",
-    "test": "react-scripts test",
-    "eject": "react-scripts eject"
-  },
-  "eslintConfig": {
-    "extends": [
-      "react-app",
-      "react-app/jest"
-    ]
-  },
-  "browserslist": {
-    "production": [
-      ">0.2%",
-      "not dead",
-      "not op_mini all"
-    ],
-    "development": [
-      "last 1 chrome version",
-      "last 1 firefox version",
-      "last 1 safari version"
-    ]
+    "start": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
   },
   "devDependencies": {
     "@types/node": "^25.2.0",
     "@types/react": "^19.2.10",
     "@types/react-dom": "^19.2.3",
     "@types/react-router-dom": "^5.3.3",
-    "typescript": "^5.9.3"
+    "@vitejs/plugin-react": "^5.1.4",
+    "typescript": "^5.9.3",
+    "vite": "^7.3.1"
   }
 }