fix: add transaction rollback and session validation to BaseCollector

- Add session validation in __init__ to ensure database session is not None
- Implement transaction rollback handling in complete_job() for exception safety
- Implement transaction rollback handling in fail_job() for exception safety
- Improve exception handling in run() to gracefully handle fail_job failures while preserving original exception

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/services/collectors/base.py

@@ -14,6 +14,8 @@ class BaseCollector(ABC):
     """Base class for all data collectors."""
 
     def __init__(self, db: Session):
+        if db is None:
+            raise ValueError("Database session cannot be None")
         self.db = db
         self.job_name = self.__class__.__name__
         self.job_log: Optional[JobLog] = None
@@ -32,18 +34,26 @@ class BaseCollector(ABC):
     def complete_job(self, records_count: int):
         """Mark job as completed."""
         if self.job_log:
-            self.job_log.status = "success"
-            self.job_log.finished_at = datetime.utcnow()
-            self.job_log.records_count = records_count
-            self.db.commit()
+            try:
+                self.job_log.status = "success"
+                self.job_log.finished_at = datetime.utcnow()
+                self.job_log.records_count = records_count
+                self.db.commit()
+            except Exception:
+                self.db.rollback()
+                raise
 
     def fail_job(self, error_msg: str):
         """Mark job as failed."""
         if self.job_log:
-            self.job_log.status = "failed"
-            self.job_log.finished_at = datetime.utcnow()
-            self.job_log.error_msg = error_msg
-            self.db.commit()
+            try:
+                self.job_log.status = "failed"
+                self.job_log.finished_at = datetime.utcnow()
+                self.job_log.error_msg = error_msg
+                self.db.commit()
+            except Exception:
+                self.db.rollback()
+                raise
 
     @abstractmethod
     def collect(self) -> int:
@@ -60,6 +70,9 @@ class BaseCollector(ABC):
             records = self.collect()
             self.complete_job(records)
         except Exception as e:
-            self.fail_job(str(e))
+            try:
+                self.fail_job(str(e))
+            except Exception:
+                pass  # Log update failed, but original exception is more important
             raise
         return self.job_log