directPathForEndpoint hand-rolled Tailscale detection that called any 100.x
address a tailnet and missed Tailscale IPv6, so the same endpoint could be
labelled differently from the direct connection log. It now uses the shared
isTailscaleEndpoint. Also: a stale no-relay comment, a duplicate routing doc
line, and the overlay chain settling to Promise<void>.
Co-authored-by: mmarabel <166927047+mmarabel@users.noreply.github.com>
Co-authored-by: Neil <neil@stably.ai>