Basics 0.4.9 — bounded TidesDB value-log retention

Add an opt-in logical-write byte budget and checked memtable flush to the TidesDB wrapper. Flushes occur before the next transaction, allowing obsolete separated values to be reclaimed without changing successful-commit semantics. Existing consumers keep their current behavior unless they select a budget.

Validated with the pinned TidesDB 10 master library, focused durability/crash-reopen tests, and a repeated-overwrite comparison.