refactor(obicompactvec): unify bit and int vector slice views

Refactors column and matrix access to use unified `BitSliceView` and `IntSliceView` abstractions, replacing legacy `PackedCol`/`IntColView` types. Introduces `BitSlice`/`IntSlice` traits for zero-copy, trait-based bitwise and arithmetic operations across persistent and temporary vector types. Removes deprecated in-memory `MemoryBitVec` and `MemoryIntVec` implementations and their tests, while updating dependent crates to use the new view-based API and `BitSliceMut` trait.

src/obilayeredmap/src/layer.rs

@@ -6,7 +6,6 @@ use obicompactvec::{
     PersistentBitMatrix, PersistentBitMatrixBuilder,
     PersistentCompactIntMatrix, PersistentCompactIntMatrixBuilder,
 };
-use obicompactvec::traits::BitSliceMut;
 use obikseq::CanonicalKmer;
 use obiskio::{UnitigFileReader, UnitigFileWriter};
 

src/obilayeredmap/src/layered_store.rs

@@ -102,7 +102,6 @@ mod tests {
         PersistentBitMatrix, PersistentBitMatrixBuilder,
         PersistentCompactIntMatrix, PersistentCompactIntMatrixBuilder,
     };
-    use obicompactvec::traits::BitSliceMut;
     use tempfile::tempdir;
 
     fn make_int_matrix(cols: &[&[u32]]) -> (tempfile::TempDir, PersistentCompactIntMatrix) {