refactor: extract admin business logic to services, introduce job queue, add derived index helpers

- Move DB operations from routes/admin.py to services/admin.py (get_logs_context, query_summary_statuses, retry_failed, delete/reset operations)
- Add services/jobs.py with Job/JobEvent-based async job queue (create_job, run_job, enqueue_job)
- Add services/derived.py with FTS5 reindex and paper index deletion helpers
- Refactor scheduler to use job queue instead of direct pipeline calls
- Add heartbeat_at/expires_at to TaskLock for lock health tracking
- Remove DESIGN_REVIEW.md
- Update tests: remove redundant integration tests, add unit tests for new services

app/services/crawler.py

@@ -4,7 +4,7 @@ import logging
 from datetime import date as date_type, datetime, timezone
 
 import httpx
-from sqlalchemy import select, text
+from sqlalchemy import select
 from sqlalchemy.orm import Session
 
 from app.config import settings
@@ -16,6 +16,7 @@ from app.models import (
     SummaryState,
     SummaryStatus,
 )
+from app.services.derived import reindex_paper_fts
 from app.utils import make_http_client, recent_date_strs, utc_now
 
 logger = logging.getLogger(__name__)
@@ -143,21 +144,7 @@ def upsert_papers(db: Session, papers_raw: list[dict], paper_date: str) -> list[
 
             db.add(SummaryStatus(paper_id=paper.id, status=SummaryState.PENDING))
 
-            authors_text = ", ".join(meta["authors"])
-            tags_text = ", ".join(meta["tags"])
-            db.execute(
-                text(
-                    "INSERT INTO papers_fts(rowid, title_en, abstract, authors, tags) "
-                    "VALUES (:id, :title, :abstract, :authors, :tags)"
-                ),
-                {
-                    "id": paper.id,
-                    "title": meta["title_en"],
-                    "abstract": meta["abstract"] or "",
-                    "authors": authors_text,
-                    "tags": tags_text,
-                },
-            )
+            reindex_paper_fts(db, paper)
 
             new_papers.append(paper)
             logger.debug("Inserted new paper: %s", arxiv_id)