feat: implement persistent layered index and chunked binary format

Introduce the `obilayeredmap` specification and persistent MPHF-based index architecture for incremental multi-dataset indexing. Implement chunked binary serialization with a fixed `u8` k-mer count limit (256) and overlapping super-kmer segments. Add memory-mapped I/O and a companion `.idx` index file for allocation-free, O(1) unitig access. Update MkDocs navigation, enhance the k-mer comparison script, and add comprehensive tests for serialization, partitioning, and file I/O pipelines.

src/obikpartitionner/Cargo.toml

@@ -3,6 +3,13 @@ name = "obikpartitionner"
 version = "0.1.0"
 edition = "2024"
 
+[dev-dependencies]
+tempfile = "3"
+obikseq   = { path = "../obikseq",   features = ["test-utils"] }
+obiskbuilder = { path = "../obiskbuilder" }
+obiread   = { path = "../obiread" }
+obikrope  = { path = "../obikrope" }
+
 [dependencies]
 niffler = "3.0.0"
 remove_dir_all = "0.8"