0dcb5dd6c2
- rename `obirope` → `obikroper`
- replace legacy rope with new in-place, Cell-based implementation
- add ForwardCursor/Backward Cursor & SeekMode support (no more BytesMut)
- update all dependents:
- obiread: switch to Rope + cursors, remove tape.rs
• chunk iterator yields `Rope` instead of Vec<Bytes>
- obiskbuilder: use ForwardCursor over Rope
- remove bytes dependency from affected crates