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/services/embedder.py

@@ -189,11 +189,15 @@ def index_paper(paper_id: str, texts_dict: dict | None = None) -> bool:
 
             db = SessionLocal()
             try:
-                paper = db.execute(
-                    select(Paper)
-                    .where(Paper.arxiv_id == paper_id)
-                    .options(joinedload(Paper.tags), joinedload(Paper.summary))
-                ).unique().scalar_one_or_none()
+                paper = (
+                    db.execute(
+                        select(Paper)
+                        .where(Paper.arxiv_id == paper_id)
+                        .options(joinedload(Paper.tags), joinedload(Paper.summary))
+                    )
+                    .unique()
+                    .scalar_one_or_none()
+                )
                 if not paper:
                     logger.warning("Paper %s not found for indexing", paper_id)
                     return False