fix: 添加热门概念静态数据的 mock handler

- 拦截 /data/concept/latest.json 请求
- 返回 mock 生成的热门概念数据
- 修复 HeroPanel 热门概念模块无数据问题

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

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

src/mocks/handlers/concept.js

@@ -848,5 +848,18 @@ export const conceptHandlers = [
             lv1_id: lv1Id,
             lv2_id: lv2Id
         });
+    }),
+
+    // 热门概念静态数据文件（HeroPanel 使用）
+    http.get('/data/concept/latest.json', async () => {
+        await delay(200);
+        console.log('[Mock Concept] 获取热门概念静态数据');
+
+        const concepts = generatePopularConcepts(30);
+
+        return HttpResponse.json({
+            date: new Date().toISOString().split('T')[0],
+            results: concepts
+        });
     })
 ];