feat(sprint1-step2): core economy TS + useEconomy hook (lazy calc) + 13 tests vitest

Frontend/package.json

@@ -7,7 +7,8 @@
     "dev": "vite",
     "build": "vite build",
     "lint": "eslint . --ext js,jsx --report-unused-disable-directives --max-warnings 0",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "test": "vitest run"
   },
   "dependencies": {
     "react": "^18.2.0",
@@ -18,13 +19,15 @@
     "sass": "^1.69.5"
   },
   "devDependencies": {
-    "@types/react": "^18.2.37",
+    "@types/react": "^18.3.28",
     "@types/react-dom": "^18.2.15",
     "@vitejs/plugin-react": "^4.2.0",
     "eslint": "^8.53.0",
     "eslint-plugin-react": "^7.33.2",
     "eslint-plugin-react-hooks": "^4.6.0",
     "eslint-plugin-react-refresh": "^0.4.4",
-    "vite": "^5.0.0"
+    "typescript": "^5.9.3",
+    "vite": "^5.0.0",
+    "vitest": "^4.1.0"
   }
 }