fix: PDF extraction bbox compatibility, update date formats, and bump max retries

- Fix bbox format detection in pdf_image_extractor (support Rect and tuple)
- Update date display format to include year (%Y-%m-%d) across templates
- Increase SUMMARY_MAX_RETRIES from 1 to 2 for better error recovery
- Widen date input field for better usability

app/templates/partials/paper_card.html

@@ -20,7 +20,7 @@
         {% endif %}
       </a>
     </h2>
-    <span class="paper-upvotes" title="数据更新于 {{ paper.crawled_at.strftime('%m-%d %H:%M') if paper.crawled_at else '' }}">👍 {{ paper.upvotes }}</span>
+    <span class="paper-upvotes" title="数据更新于 {{ paper.crawled_at.strftime('%Y-%m-%d %H:%M') if paper.crawled_at else '' }}">👍 {{ paper.upvotes }}</span>
     {% if variant == 'search' and distances and paper.arxiv_id in distances %}
     <span class="similarity-score" title="语义相似度距离">
       🎯 {{ "%.3f"|format(distances[paper.arxiv_id]) }}