feat: add dataset item images

apps/web_v1/src/App.css

@@ -965,6 +965,15 @@
   margin-bottom: 24px;
 }
 
+.explore-article-image {
+  display: block;
+  width: 100%;
+  max-height: 420px;
+  margin: 0 0 24px;
+  border-radius: 12px;
+  object-fit: cover;
+}
+
 .explore-article-content {
   margin: 0;
   color: var(--senlin-text);

apps/web_v1/src/api/dataset.ts

@@ -24,6 +24,7 @@ export type DatasetItemDTO = {
   summary: string
   content: string
   url: string
+  imageUrl: string
   status: 'unread' | 'read' | 'archived'
   starred: boolean
   publishedAt: string | null

apps/web_v1/src/pages/workspace-explore.tsx

@@ -445,6 +445,9 @@ export function WorkspaceExplorePage({
                   <Text type="secondary">{selectedSource.name}</Text>
                   <Text type="secondary">{itemTime(selected)}</Text>
                 </Space>
+                {selected.imageUrl ? (
+                  <img className="explore-article-image" src={selected.imageUrl} alt="" />
+                ) : null}
                 <Paragraph className="explore-article-content">{selected.content || selected.summary || '暂无正文'}</Paragraph>
               </article>
             </Card>