feat: 事件详情页 URL ID 加密，防止用户遍历

- 新增 idEncoder.ts 工具：使用 Base64 + 前缀混淆加密 ID
- 路由改为查询参数形式：/event-detail?id=xxx
- 更新所有入口使用 getEventDetailUrl() 生成加密链接
- 兼容旧链接：纯数字 ID 仍可正常访问

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/components/Navbars/components/FeatureMenus/FollowingEventsMenu.js

@@ -21,6 +21,7 @@ import { ChevronDownIcon } from '@chakra-ui/icons';
 import { FiCalendar } from 'react-icons/fi';
 import { useNavigate } from 'react-router-dom';
 import { useFollowingEvents } from '../../../../hooks/useFollowingEvents';
+import { getEventDetailUrl } from '@/utils/idEncoder';
 
 /**
  * 关注事件下拉菜单组件
@@ -86,7 +87,7 @@ const FollowingEventsMenu = memo(() => {
                                         <MenuItem
                                             key={ev.id}
                                             _hover={{ bg: 'gray.50' }}
-                                            onClick={() => navigate(`/event-detail/${ev.id}`)}
+                                            onClick={() => navigate(getEventDetailUrl(ev.id))}
                                         >
                                             <HStack justify="space-between" w="100%">
                                                 <Box flex={1} minW={0}>