revert(icom): drop Wake-on-LAN — the deck does not honour it

Tried on the real IC-7760: the magic packet wakes nothing; Icom's own
mechanism is the network-standby session plus the CI-V power-on, which
OpsLog already does. The MAC store and the WOL sender go, and the changelog
entry with them. The CI-V pump now says once per session that the client
pings are armed — invisible pings read as absent pings.

app.go

@@ -159,7 +159,6 @@ const (
 	keyCATIcomNetUser      = "cat.icom.net.user"       // Icom network: Network User1 ID
 	keyCATIcomNetPass      = "cat.icom.net.pass"       // Icom network: Network User1 password
 	keyCATIcomNetAudio     = "cat.icom.net.audio"      // Icom network: stream RX audio on 50003 (experimental)
-	keyCATIcomNetMAC       = "cat.icom.net.mac"        // the rig's MAC, learned at login, for Wake-on-LAN
 	keyAudioMonitorOn      = "audio.monitor.on"        // play the network RX audio through the Listening device (the stream itself stays open for the recorder either way)
 	keyCATTCIHost          = "cat.tci.host"            // TCI host (Expert Electronics SunSDR / ExpertSDR2)
 	keyCATTCIPort          = "cat.tci.port"            // TCI WebSocket port (default 40001)
@@ -1297,12 +1296,6 @@ func (a *App) startup(ctx context.Context) {
 	}
 	a.startQSORecorderIfEnabled()
 
-	// The Icom network backend remembers the rig's MAC so a deck switched
-	// fully off can be woken with a magic packet when a session is wanted.
-	cat.SetIcomMACStore(
-		func(mac string) { a.setSetting(keyCATIcomNetMAC, mac) },
-		func() string { return a.settingOr(keyCATIcomNetMAC, "") },
-	)
 	a.reloadCAT()
 
 	// The QSO logbook lives where the ACTIVE PROFILE points it: the local SQLite