Final pipeline stages inherit the real TTY so tools like less/vim work; capture
mode still forces color when needed. Pre-colored external output is not
re-painted, table widths use visible length, and which -a lists all PATH matches.

Live syntax highlighting, Tab path completion, and Ctrl+C line cancel
via a raw TTY editor (+Bc). Process environment uses Nushell-style
$env / $env.VAR / $env.FOO = value; non-TTY falls back to edlin.

Pretty `to json` / `from json`, ANSI table output with NO_COLOR, and
OTP shell history with Ctrl+R reverse-i-search in the interactive REPL.