- Added native process tree killing and listing functions via new `ps` module in pi-natives crate with platform-specific implementations (Linux /proc, macOS libproc, Windows CreateToolhelp32Snapshot).
- Refactored process termination logic to prioritize native process tree killing when available, improving reliability of process cleanup across platforms.
- Removed detached process spawning across codebase (bash-executor, shell-session, kernel, lsp client, markitdown conversion) in favor of native process tree management.
- Simplified ptree module by removing managed children tracking and postmortem cleanup hooks, delegating process lifecycle management to native implementations.