fix hanging manual snapshot task

internal/tasks/monthlyAggregate.go

@@ -99,6 +99,13 @@ func (c *CronTask) aggregateMonthlySummary(ctx context.Context, targetMonth time
 		c.Logger.Error("failed to aggregate monthly inventory", "error", err, "month", targetMonth.Format("2006-01"))
 		return err
 	}
+	// Backfill missing creation times to the start of the month for rows lacking creation info.
+	if _, err := dbConn.ExecContext(ctx,
+		`UPDATE `+monthlyTable+` SET "CreationTime" = $1 WHERE "CreationTime" IS NULL OR "CreationTime" = 0`,
+		monthStart.Unix(),
+	); err != nil {
+		c.Logger.Warn("failed to normalize creation times for monthly summary", "error", err, "table", monthlyTable)
+	}
 	rowCount, err := db.TableRowCount(ctx, dbConn, monthlyTable)
 	if err != nil {
 		c.Logger.Warn("unable to count monthly summary rows", "error", err, "table", monthlyTable)