Introduces `PersistentBitMatrix` and `PersistentCompactIntMatrix` to replace single-file vector storage with a column-major, directory-based layout. Each column is persisted as an individual file alongside a lightweight `meta.json` for dimension tracking. Migrates `obilayeredmap` to use these multi-column structures, updating Rust APIs, query return types, and build signatures. Includes comprehensive documentation, unit and integration tests for persistence and accessors, and refactors distance calculation helpers.
Introduces PersistentBitVec, a dense, memory-mapped bit vector optimized for bulk u64-word operations and SIMD acceleration, complete with bitwise operators and Jaccard/Hamming distance metrics. Upgrades PersistentCompactIntVec to a unified .pciv format using 64-bit indices and offsets, consolidating the binary layout and updating builder/reader lifecycles accordingly. Adds corresponding documentation, updates MkDocs navigation, and implements a comprehensive test suite for persistence round-trips, edge cases, and metric accuracy.