refactor: rename obikpartitionner crate to obikpartition

Update Cargo manifests, dependency paths, and Rust imports across the workspace to reflect the `obikpartitionner` to `obikpartition` rename. Synchronize architecture and implementation documentation with the new module structure. Fix minor syntax issues in test assertions to ensure compilation compatibility. No behavioral or API changes are introduced.

DevDocMD/implementation/mphf.md

@@ -6,7 +6,7 @@ Kmer indexing per partition proceeds in two phases. The separation is necessary
 
 ### Phase 1 — provisional MPHF + kmer spectrum
 
-Implemented in `obikpartitionner::KmerPartition::count_kmer()` → `count_partition()`.
+Implemented in `obikpartition::KmerPartition::count_kmer()` → `count_partition()`.
 
 1. **External sort**: read the dereplicated superkmer file; extract the raw `u64` canonical kmer value for every kmer of every superkmer. Sort in RAM-bounded chunks (adaptive budget: 40% of available RAM ÷ n_threads, minimum 1 M kmers per chunk), then k-way merge with inline dedup. Result: `sorted_unique.bin` — a flat array of f0 distinct sorted `u64` values. Exact kmer count f0 is known at this point.
 2. **Build provisional MPHF** (ptr_hash, same configuration as phase 2) over `sorted_unique.bin` using `new_from_par_iter`. Delete `sorted_unique.bin` immediately after. Persist to `mphf1.bin`.
@@ -148,7 +148,7 @@ MphfLayer::build_approx_evidence(dir, b, z)
 
 There is no `build_evidence` dispatch wrapper. Callers choose the appropriate post-hoc build directly.
 
-In `obikpartitionner`, `build_index_layer` receives `block_bits: u8` from `IndexConfig::block_bits` and forwards it directly to `Layer::build` and `Layer::build_approx_evidence`.
+In `obikpartition`, `build_index_layer` receives `block_bits: u8` from `IndexConfig::block_bits` and forwards it directly to `Layer::build` and `Layer::build_approx_evidence`.
 
 ### Membership verification