admin: System page with restart steps, Record calls on the Calling tab

System shows whether telephony runs and needs a restart, and how to restart it
(docker compose restart asterisk); the dashboard's restart warning, the Network hint and
the public IP email point there. The user drawer's Calling tab gets the Record calls
select the spec listed (recordMode, already in the dialplan). e2e m11-system.mjs.

Task: M11-T7

docs/admin-guide/network.md

@@ -30,7 +30,7 @@ the wrong place.
      ("Public IP changed to …").
    - **Then restart telephony** so Asterisk uses the new address: on the server, run
      `docker compose restart asterisk` (calls in progress drop). The dashboard shows "SIP port or
-     transport changes need a telephony restart" until you do.
+     transport changes need a telephony restart" until you do, and **System** shows the command.
 
 ![Settings → Network](img/settings-network.png)