Child processes (Git Bash/MSYS2) strip the ENABLE_VIRTUAL_TERMINAL_INPUT
flag from the shared stdin console handle, corrupting terminal input.
Re-enable the flag after every child process exits in bash.js, bg-shell,
and cache FFI handles in pi-tui for cheap repeated calls.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
