* fix(serve): keep `orca serve` running while it probes the login shell
`orca serve` started from an interactive terminal stopped itself ("[1]+
Stopped") before printing its pairing link. orcad inherits the terminal
and probes the login shell with `$SHELL -ilc`; an interactive bash 5 or
zsh takes the terminal's foreground job, so orcad's next terminal access
raised SIGTTOU/SIGTTIN. Give both shell probes (login environment and
PATH) a POSIX session of their own so they never hold a controlling
terminal. Windows keeps attached spawns, where `detached` would open a
console.
Refs #38347
* fix(serve): end a detached shell probe with its owner and on timeout
A probe in its own session no longer receives the terminal's Ctrl+C or
hangup, so a hung rc could outlive `orca serve`. Kill the probe's process
group by its own pid when it times out and when its owner exits while it
still runs; orcad and Electron turn INT/TERM into an exit, so a Ctrl+C
reaches it that way. No signal listeners: one would replace Electron's
graceful signal quit. The timeout now also ends what the rc started, not
just the shell.
Refs #38347
Neil
47e8985117