feat: 添加中国地图交互功能

- 新增 react-simple-maps 地图库
- 实现中国省级行政区划地图（34 个省份）
- 首页集成地图组件，点击省份跳转城市列表
- 悬停显示省份名称，热力图颜色表示内容丰富度
- 重构 stores 导出方式，支持 hooks 模式

frontend/package.json

@@ -4,12 +4,15 @@
   "private": true,
   "dependencies": {
     "axios": "^1.6.0",
+    "d3-geo": "^3.1.1",
+    "d3-scale": "^4.0.2",
     "mobx": "^6.12.0",
     "mobx-react-lite": "^4.0.7",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "react-router-dom": "^6.20.0",
     "react-scripts": "5.0.1",
+    "react-simple-maps": "^3.0.0",
     "styled-components": "^6.1.0",
     "web-vitals": "^2.1.4"
   },
@@ -45,4 +48,4 @@
     "prettier": "^3.1.0"
   },
   "proxy": "http://localhost:8000"
-}
+}