Function create_fenced_range_scan_iterator 

pub fn create_fenced_range_scan_iterator<'a, 'txn: 'a, S: KVStore + 'txn>(
    txn: &'a mut SqlTransaction<'txn, S>,
    table_meta: &TableMetadata,
    constraint: &StorageRangeConstraint,
) -> Result<RangeBoundedScanIterator<'a>>

Creates the only scan iterator intended for a fenced remote range worker.

Unlike create_scan_iterator, this entry point rejects an ordinary local transaction and always uses concrete scan_range bounds. The caller has already pinned the catalog, schema, and index identities in constraint.