nav: 三级导航分页结构 + 中国地区索引

- 02-game-design 地图结构重写：洲→国家→城市，3x3棋盘分页
- 中国 40 城按 8 地区分组（华北/东北/华东/华中/华南/西南/西北/港澳）
- 导航索引数据：continents/index + asia + regions/china + pagination工具

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

js/content/regions/china.js

@@ -0,0 +1,73 @@
+// 中国地区列表 — 8 个地区，1 页
+
+export const chinaRegions = [
+  {
+    id: 'north_china',
+    name: '华北',
+    nameEn: 'North China',
+    sortOrder: 1,
+    themeColor: '#CC2936',
+    cityIds: ['beijing', 'tianjin', 'shijiazhuang', 'taiyuan', 'hohhot'],
+  },
+  {
+    id: 'northeast',
+    name: '东北',
+    nameEn: 'Northeast',
+    sortOrder: 2,
+    themeColor: '#5DADE2',
+    cityIds: ['shenyang', 'changchun', 'harbin', 'dalian'],
+  },
+  {
+    id: 'east_china',
+    name: '华东',
+    nameEn: 'East China',
+    sortOrder: 3,
+    themeColor: '#2ECC71',
+    cityIds: ['shanghai', 'nanjing', 'hangzhou', 'hefei', 'fuzhou', 'nanchang', 'jinan', 'suzhou', 'xiamen', 'qingdao', 'ningbo'],
+  },
+  {
+    id: 'central_china',
+    name: '华中',
+    nameEn: 'Central China',
+    sortOrder: 4,
+    themeColor: '#E67E22',
+    cityIds: ['zhengzhou', 'wuhan', 'changsha'],
+  },
+  {
+    id: 'south_china',
+    name: '华南',
+    nameEn: 'South China',
+    sortOrder: 5,
+    themeColor: '#FF6B6B',
+    cityIds: ['guangzhou', 'shenzhen', 'nanning', 'haikou', 'sanya'],
+  },
+  {
+    id: 'southwest',
+    name: '西南',
+    nameEn: 'Southwest',
+    sortOrder: 6,
+    themeColor: '#9B59B6',
+    cityIds: ['chengdu', 'chongqing', 'guiyang', 'kunming', 'lhasa'],
+  },
+  {
+    id: 'northwest',
+    name: '西北',
+    nameEn: 'Northwest',
+    sortOrder: 7,
+    themeColor: '#F4D03F',
+    cityIds: ['xian', 'lanzhou', 'xining', 'yinchuan', 'urumqi'],
+  },
+  {
+    id: 'hk_macao',
+    name: '港澳',
+    nameEn: 'HK & Macao',
+    sortOrder: 8,
+    themeColor: '#E74C3C',
+    cityIds: ['hongkong', 'macao'],
+  },
+]
+
+// 分页：1 页（8 项 ≤ 9）
+export const chinaRegionPages = [chinaRegions]
+
+export default chinaRegions