0ae8efd649
- Integrated 17 new coreutils-based shell builtins including `diff`, `date`, `ln`, `stat`, `seq`, `touch`, and others. - Refactored vendored utilities to execute as in-process shell builtins by routing I/O, environment access, and path resolution through `pi_uutils_ctx`. - Disabled process-level modifications (e.g., clock setting, hostname modification) to ensure safety and scope adherence within the shell environment. - Implemented shell-specific features such as cancellation polling, custom exit code management, and efficient output streaming for all new builtins.