v0.7.2

Fixed

• Fixed nightly DB/crash soak failures where stale cross-blob routes could reach
  a delete-fenced blob. DB no longer runs GUID-only background auto-merge;
  DB-wide merge stays rooted in live trees through explicit compaction. The
  route cache is now restricted to root-child crossings, and walkers restart
  from the root when they encounter a delete-fenced child instead of treating it
  as NotFound.
• DB::view now uses the same fenced snapshot capture path as Tree::view,
  so multi-tree views cannot capture parent/child topology from mixed write
  generations.
• Merge eligibility now rejects snapshot-shared child blobs, preventing
  maintenance from deleting a blob still referenced by a live snapshot.