Introduces `TempCompactIntVec` and `TempBitVec` as temporary, file-backed intermediates to replace eager in-memory vectors, enabling OS-level paging under memory pressure. Updates the `MatrixGroupOps` trait to return `io::Result` types, allowing proper error propagation and supporting chunked accumulation for large column groups. Includes builder patterns with `.freeze()` finalization, automatic `TempDir` cleanup on drop, and necessary test updates to handle the new fallible signatures. Also fixes `Cargo.toml` section ordering.
Eric Coissac