v0.3.2

Added

• Added scoped read transactions via Tree::view(prefix, |view| ...).
  A view captures the prefix's reachable blob frames, releases the
  live tree, and serves point reads plus record/key range scans from
  that stable frame set.
• Added a Verus model under verified/ for the ART shape invariants
  that matter most to the persistent tree: node capacity classes,
  grow/shrink thresholds, prefix splits, delimiter rollup bounds,
  and leaf extent alignment.
• Added sled as an optional benchmark comparator in the standalone
  benchmark package.

Changed

• Renamed Tree::scan_prefix(prefix) to Tree::scan(prefix).
  The old name is not kept as a compatibility alias; use
  Tree::range().prefix(prefix) when the explicit builder form is
  clearer.
• Narrowed the supported public import surface to crate-root
  re-exports (holt::{Tree, TreeBuilder, RangeEntry, ...}); the
  internal api module is no longer public.
• Split benchmarks into a non-published holt-bench package under
  benches/Cargo.toml. Normal holt users no longer pull
  Criterion, RocksDB, SQLite, sled, or their transitive dependencies
  when depending on the crate.
• Replaced the push-time CI benchmark with a Holt-only regression
  target. Full RocksDB/SQLite/sled comparisons remain available
  through the standalone benchmark package.