Add WieldItemOptimistic (instant optimistic wield — sets ContainerId=WielderId=player,
CurrentlyEquippedLocation=equipMask, snapshots pre-wield position) and extend the
_pendingMoves tuple to carry the pre-move EquipMask so RollbackMove restores EQUIPPED
state faithfully on server rejection. Shared RecordPending helper replaces the inline
snapshot block in MoveItemOptimistic.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>