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/scheduler.py

@@ -11,8 +11,7 @@ from zoneinfo import ZoneInfo
 
 from app.config import settings
 from app.database import SessionLocal
-from app.services.pipeline import run_pipeline
-from app.services.crawler import refresh_upvotes
+from app.services.jobs import create_job, run_job
 from app.utils import today_str
 
 logger = logging.getLogger(__name__)
@@ -112,7 +111,13 @@ async def _daily_pipeline() -> None:
 
     db: Session = SessionLocal()
     try:
-        await run_pipeline(db, today, owner="daily_pipeline")
+        job = create_job(
+            db,
+            "pipeline_daily",
+            owner="daily_pipeline",
+            payload={"target_date": today},
+        )
+        await run_job(db, job.id)
     except RuntimeError:
         logger.warning("Daily pipeline already running for %s, skipping", today)
     except Exception:
@@ -125,7 +130,8 @@ async def _upvote_refresh() -> None:
     """刷新最近 N 天论文的 upvotes。"""
     db: Session = SessionLocal()
     try:
-        result = await refresh_upvotes(db)
+        job = create_job(db, "refresh_upvotes", owner="upvote_refresh", payload={})
+        result = await run_job(db, job.id)
         logger.info(
             "Upvote refresh completed: status=%s updated=%d",
             result.get("status"),