v0.4.1

Added

• Added DB-specific crash soak coverage. The new holt-soak --mode db-crash repeatedly kills cross-tree DB::atomic writers
  and verifies that every fsynced acknowledged transaction replays
  all of its tree mutations after reopen.
• Added a Verus model for the DB catalog state machine: live trees are
  the only visible catalog entries, dropped trees stay hidden until
  finalized, and user tree-id allocation remains monotonic while
  skipping the reserved catalog id.

Changed

• Optimized DB::atomic batch grouping with a per-batch tree-name
  resolution cache. Repeated operations for the same named tree now
  avoid repeated catalog lookups, tree-state opens, and linear group
  scans before taking the ordered mutation gates.