Adds opt-in `gateway.tailscale.preserveFunnel`. When `tailscale.mode = "serve"`
and an externally configured Tailscale Funnel route already covers the gateway
port, OpenClaw checks `tailscale funnel status --json` before re-applying
`tailscale serve` and skips both Serve and the `resetOnExit` teardown for that
run, preserving operator-managed Funnel exposure across gateway restarts.
The Funnel-status parser handles every documented Tailscale target scheme
(http, https, https+insecure) via an RFC 3986 scheme strip, plus loopback
hostnames (127.0.0.1, localhost, ::1) and bare-port forms. AllowFunnel-disabled
hosts and other-port routes are ignored.
Closes#57241.
60f1b1f8d9