Measured on a live update: the server was back in ~9s but stayed
unreachable for ~96s, because releasing the tunnel on shutdown forces
the replacement tunnel's hostname route through 1-2 minutes of edge
propagation. An update handoff always brings a server right back
(new version or rollback), so the tunnel is never orphaned; skip the
release when the launcher state file records a pending update. The
next boot respawns the connector from the stored config against the
same tunnel and is reachable as soon as it connects.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>