fix: 客户评价页补全截图/标签/关键词数据

- reviews表新增screenshot/scenes/concerns字段
- API映射从数据库读取这些字段，不再硬编码为空
- 修复客户高频关键词不显示的问题

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

server/api/content/[key].get.js

@@ -18,11 +18,11 @@ function buildFromEntityTable(db, key, siteData) {
           nickname: r.author,
           travelDate: r.date,
           productVersion: r.title,
-          screenshot: '',
+          screenshot: r.screenshot || '',
           content: r.content,
           rating: r.rating,
-          scenes: [],
-          concerns: [],
+          scenes: r.scenes ? JSON.parse(r.scenes) : [],
+          concerns: r.concerns ? JSON.parse(r.concerns) : [],
         }))
       // 合并 site_content 的 summary（如果有/��
       const summary = siteData?.summary || {