The dry-run that sizes a country selection had a 60 s limit. Its runtime
scales with land area, so large selections went over it on ordinary
hardware: Canada alone takes 41 s on a fast box, US+CA+MX 61 s. The user
got a generic 500 with an empty stderr, indistinguishable from a real
failure because pmtiles buffers its output and loses it on SIGTERM.
- Raise the limit to 10 minutes.
- Detect a timeout from execFile's killed/signal/code (isExecTimeout) and
return a 504 with a plain message instead of a 500.
- Let the country picker show the server's message inline; the call no
longer goes through catchInternal's generic toast.
Closes#1258
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
