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/database.py

@@ -82,15 +82,12 @@ def _migrate(engine) -> None:
         for table, columns in _MIGRATIONS.items():
             # 获取已有列名
             existing = {
-                row[1]
-                for row in conn.execute(text(f"PRAGMA table_info({table})"))
+                row[1] for row in conn.execute(text(f"PRAGMA table_info({table})"))
             }
             for col_name, col_type in columns:
                 if col_name not in existing:
                     conn.execute(
-                        text(
-                            f"ALTER TABLE {table} ADD COLUMN {col_name} {col_type}"
-                        )
+                        text(f"ALTER TABLE {table} ADD COLUMN {col_name} {col_type}")
                     )
                     logger.info("Migrated: %s.%s added", table, col_name)
         conn.commit()