Introduces the `obikpartition` crate containing the `KmerPartition` struct to manage open layers in sequential order. The `open` constructor eagerly initializes layers under a specified directory, while the `find` method returns the index of the first layer containing a given k-mer. Dependencies are strictly scoped to `obilayeredmap` and `obikseq`, with unit tests validating layer ingestion and single-kmer lookup behavior. Batch lookups and further migration are deferred to a subsequent phase.
Eric Coissac
164e879585