Fixed captured-version scans reading a newer row payload after a concurrent UPDATE reused its arena slot. These scans now read the payload retained by the visible version, preserving snapshot values, filter results, ordering, and aggregates.
Removed the unused storage sorted-limit and RowIndex materialization APIs, plus the MVCC StreamingResult module. This removes public Rust symbols; SQL queries continue to use the existing index-order and top-k scans.