chore: add test infrastructure and update risk router

- Add vitest config and unit tests for components, api, stores
- Add Playwright e2e test for user flows
- Add backend test files
- Update risk.py with LOD grid KDTree optimization

frontend/package.json

@@ -20,14 +20,18 @@
   },
   "devDependencies": {
     "@playwright/test": "^1.59.1",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^14.3.1",
     "@types/leaflet": "^1.9.8",
     "@types/react": "^18.2.55",
     "@types/react-dom": "^18.2.19",
     "@vitejs/plugin-react": "^4.2.1",
     "autoprefixer": "^10.4.17",
+    "jsdom": "^24.1.3",
     "postcss": "^8.4.35",
     "tailwindcss": "^3.4.1",
     "typescript": "^5.3.3",
-    "vite": "^5.1.0"
+    "vite": "^5.1.0",
+    "vitest": "^1.6.1"
   }
 }