fix(tci): resubscribe to the meters at 'ready', and log what comes back

The report from a real SunSDR: transmit power and SWR still empty after the
sensors fix. The subscription went out once, at connect — while ExpertSDR3 is
still streaming its initial state dump, exactly where a unidirectional control
command can be ignored. It is now renewed every time the server says 'ready'.

The sensor messages also join the logged-on-arrival set, capped like the rest:
the next log will say whether TX_SENSORS ever arrives, which is the question —
a radio that never sends it (AetherSDR may not) and a frame that arrived and
was dropped leave the same blank meters and need opposite fixes.

internal/cat/tci.go

@@ -165,8 +165,7 @@ func (t *TCI) Connect() error {
 	if t.spotsEnabled {
 		debugLog.Printf("TCI: panorama spots are ON — spots will be sent to the radio")
 	}
-	_ = t.send("rx_sensors_enable:true,200;")
-	_ = t.send("tx_sensors_enable:true,200;")
+	t.subscribeSensors("connect")
 	if t.spotsEnabled {
 		// Forget what we thought was on the panorama at the same moment the radio
 		// is told to drop it. Kept, the memory would suppress the next spot for
@@ -461,6 +460,17 @@ func (t *TCI) SetTXAudioSource(src string) {
 }
 
 // send writes a command to the WebSocket (one writer at a time).
+// subscribeSensors asks the radio to push its meters. Nothing measures anything
+// until this goes out — the S-meter, the transmit power and the SWR are all
+// subscription-only (TCI §4.4) — and it is sent at connect AND again at every
+// "ready", because a subscription sent during the server's initial dump can be
+// dropped. 200 ms is the rate the protocol's own examples use.
+func (t *TCI) subscribeSensors(when string) {
+	e1 := t.send("rx_sensors_enable:true,200;")
+	e2 := t.send("tx_sensors_enable:true,200;")
+	debugLog.Printf("TCI: sensor subscription sent (%s): rx=%v tx=%v", when, e1, e2)
+}
+
 func (t *TCI) send(cmd string) error {
 	t.mu.Lock()
 	c := t.conn
@@ -567,6 +577,13 @@ func (t *TCI) handle(msg string) {
 		}
 	case "ready", "start":
 		t.ready = true
+		// (Re)subscribe to the meters HERE, not only at connect. ExpertSDR3
+		// dumps its whole state and then says "ready"; a unidirectional control
+		// command sent while that dump is still in flight can be ignored, and
+		// the report from a real SunSDR — transmit meters still empty after the
+		// connect-time subscription — has exactly that shape. From a goroutine:
+		// send takes t.mu, which this handler holds.
+		go t.subscribeSensors("ready")
 	case "stop":
 		t.ready = false
 	case "vfo":