- Replace `limits` module and raw binary I/O with a new high-level abstraction using obiskio::SKFileWriter
- Remove `niffler` dependency and compression logic (Gzip/Zstd/Lz4/Bgzf)
- Simplify PartitionManager to manage partitioned file writers based on kmer hashing
* Uses `n_partition_bits` for bitmask-based partition selection (2^n partitions)
- Add obiskio as a local dependency
Note: This is likely part of aligning with unified I/O primitives in the obiskio crate.