Merge branch 'tb/pack-path-walk-bitmap-delta-islands'

The pack-objects command has been updated to support reachability bitmaps and delta-islands concurrently with the `--path-walk` option, allowing faster packaging by falling back to path-walk when bitmaps cannot fully satisfy the request. * tb/pack-path-walk-bitmap-delta-islands: pack-objects: support `--delta-islands` with `--path-walk` pack-objects: extract `record_tree_depth()` helper pack-objects: support reachability bitmaps with `--path-walk` t/perf: drop p5311's lookup-table permutation