fix: guard dashboard recent_issues when backend payload omits field

src/pages/DashboardPage.tsx

@@ -58,7 +58,7 @@ export default function DashboardPage() {
             <tr><th>ID</th><th>标题</th><th>状态</th><th>优先级</th><th>类型</th></tr>
           </thead>
           <tbody>
-            {stats.recent_issues.map((i) => (
+            {(stats.recent_issues || []).map((i) => (
               <tr key={i.id}>
                 <td>#{i.id}</td>
                 <td><a href={`/issues/${i.id}`}>{i.title}</a></td>