Added src/vfs/redox_scheme.rs — VFS backend that maps scheme:name/path
to Redox kernel scheme operations via redox_syscall. Implements:
- read_dir: opens scheme dir, reads newline-separated entry list, stats
each child for metadata
- stat/exists/is_dir/is_file: via open(O_STAT) + fstat
- open_read: via open(O_RDONLY) + read, buffers file content
Gated behind #[cfg(target_os = redox)] — entire module compiles out
on Linux. Registered in vfs/mod.rs for_path() dispatch under "scheme".
Includes path parsing tests for scheme:file:/home/user paths.
This is the last remaining MC parity item (MC supports fish://, ftp://,
sftp:// on Linux — TLC now supports scheme:// on Redox).
vasilito
b4e49c761a