feat: implement researcher and publication management with sync functionality

backend/app/repositories/syncjob_repository.py

@@ -0,0 +1,28 @@
+from sqlalchemy.orm import Session
+from app.db.models import SyncJob
+from sqlalchemy.sql import func
+
+
+class SyncJobRepository:
+
+    @staticmethod
+    def start_job(db: Session, researcher_id: str):
+        job = SyncJob(
+            researcher_id=researcher_id,
+            status="running",
+            started_at=func.now()
+        )
+        db.add(job)
+        db.commit()
+        db.refresh(job)
+        return job
+
+    @staticmethod
+    def finish_job(db: Session, job: SyncJob, new_records: int, updated_records: int):
+        job.status = "finished"
+        job.new_records = new_records
+        job.updated_records = updated_records
+        job.finished_at = func.now()
+        db.commit()
+        db.refresh(job)
+        return job