Adds the `pack` subcommand to `obikmer2` for persisting presence and count matrices in sparse or dense formats. Introduces the `compact_layer` module in `obikrebuild` to merge multiple partition layers into a single layer in-place via atomic operations. Updates dependencies across `obikdump`, `obikmer2`, and `obikrebuild` to resolve new local crate references. Shifts the architecture from multi-layer accumulation to in-place compaction, removing legacy rebuild modules.
Eric Coissac
904d85f33b