The gateway unconditionally scheduled a SIGUSR1 restart after every
update.run call, even when the update itself failed (broken deps,
build errors, etc.). This left the process restarting into a broken
state — corrupted node_modules, partial builds — causing a crash loop
that required manual intervention.
Three fixes:
1. Only restart on success: scheduleGatewaySigusr1Restart is now
gated on result.status === "ok". Failed or skipped updates still
write the restart sentinel (so the status can be reported back to
the user) but the running gateway stays alive.
2. Early bail on step failure: deps install, build, and ui:build now
check exit codes immediately (matching the preflight section) so a
failed deps install no longer cascades into a broken build and
ui:build.
3. Auto-repair config during update: the doctor step now runs with
--fix alongside --non-interactive, so unknown config keys left over
from schema changes between versions are stripped automatically
instead of causing a startup validation crash.
