Add a new Reader.transfer() API with a vtable override to support efficient data transfer into a Writer.
- default implementation uses stream loop
- Linux implementation uses splice for fd-to-fd zero-copy
- File readers delegate to sendfile when possible
This allows higher-level code to transparently benefit from kernel-assisted transfer paths without changing call sites.
Add a new Reader.transfer() API with a vtable override to support efficient data transfer into a Writer.
- default implementation uses stream loop
- Linux implementation uses splice for fd-to-fd zero-copy
- File readers delegate to sendfile when possible
This allows higher-level code to transparently benefit from kernel-assisted transfer paths without changing call sites.