feat: refactor summarizer and PDF extraction pipeline

- Split summarizer into summary_generator and summary_persister modules
- Refactor pdf_image_extractor to two-phase pipeline with PicoDet layout detection
- Add layout_detector service for PicoDet-S_layout_3cls integration
- Add exceptions module with ConflictError and NotFoundError
- Improve admin dashboard with better statistics and task management
- Add design review document with system optimization suggestions
- Add new tests for crawler, pdf_downloader, pipeline, and summary_utils
- Update dependencies and configuration
- Clean up dead code and improve error handling

app/routes/compare.py

@@ -12,6 +12,8 @@ from app.utils import templates
 
 router = APIRouter()
 
+MAX_COMPARE_PAPERS = 5
+
 
 @router.get("/compare")
 def compare_page(
@@ -33,9 +35,9 @@ def compare_page(
 
     arxiv_ids = [i.strip() for i in ids.split(",") if i.strip()]
 
-    # 最多 5 篇
-    if len(arxiv_ids) > 5:
-        arxiv_ids = arxiv_ids[:5]
+    # 最多 MAX_COMPARE_PAPERS 篇
+    if len(arxiv_ids) > MAX_COMPARE_PAPERS:
+        arxiv_ids = arxiv_ids[:MAX_COMPARE_PAPERS]
 
     if not arxiv_ids:
         return templates.TemplateResponse(