* retry transient ripgrep spawn failures instead of missing binary errors
Fork/exec pressure (EAGAIN, EMFILE, ENFILE, ENOMEM, ETXTBSY) should not
trigger ripgrep-not-found guidance. Add bounded retries (max 2x) for transient
spawn failures in Quick Open and file listing, respecting cancellation signals.
Introduce RipgrepLaunchFailureError to distinguish fork/exec pressure from
unavailable ripgrep installations.
* Handle cancellation during transient spawn failure retry window
When a query is cancelled after a transient ripgrep spawn failure but before
the retry decision resumes, the cancellation must be reported to the caller
rather than proceeding with a retry attempt.
Jinjing
Neil