Refresh Relay

Force the central signaling relay to reconnect — see notify_force_reconnect.

Response shapes:

• {"status": "requested", "token_available": bool} — a reconnect was kicked off.
• {"status": "skipped", "token_available": bool, "reason": "relay_not_running" | "relay_unavailable"} — no reconnect happened. The mobile app's auto-heal loop must NOT wait for a state change in this case (it would hang forever). relay_unavailable covers the import failure (Lite-only build that ships no relay module); relay_not_running covers the module-present-but-no-instance case (daemon started without a token / pre-init / shutdown).