refactor: extract matrix helpers and improve bit iteration ergonomics

Refactor parallel matrix construction by extracting reusable `pairwise_matrix` and `pairwise2_matrix` helpers, and consolidate binary record deserialization into dedicated parsing functions. Add `set` and `iter` methods to `BitSliceMut` and `MemoryBitVec` for ergonomic bit manipulation and iteration. Standardize JSON field extraction via `meta::field`, expose `MemoryBitIter`, and improve test reliability by automatically cleaning up temporary directories.

src/obikpartitionner/src/common.rs

@@ -3,6 +3,7 @@ use std::io;
 use std::path::{Path, PathBuf};
 
 use obicompactvec::{PersistentBitVecBuilder, PersistentCompactIntVecBuilder};
+use obicompactvec::traits::BitSliceMut;
 use obilayeredmap::meta::PartitionMeta;
 use obilayeredmap::{IndexMode, OLMError};
 use obiskio::{SKError, SKResult};

src/obikpartitionner/src/select_layer.rs

@@ -6,6 +6,7 @@ use obicompactvec::{
     PersistentBitMatrix, PersistentBitMatrixBuilder, PersistentBitVecBuilder,
     PersistentCompactIntMatrix, PersistentCompactIntMatrixBuilder, PersistentCompactIntVecBuilder,
 };
+use obicompactvec::traits::BitSliceMut;
 use obilayeredmap::meta::PartitionMeta;
 use obilayeredmap::OLMError;
 use obiskio::{SKError, SKResult};