5d4f1cf6b5
- Added six builtin commands: ts, sponge, ifne, isutf8, combine, and errno to pi-shell. - Created moreutils module with independent implementations for all tools. - Added jiff dependency for timestamp and timezone functionality. - Integrated builtins into shell execution pipeline with in-process execution. - Added integration tests verifying pipe chains like ts | sponge with isutf8.