fix(icom): needle inertia for the TX meters, and room for three digits

The CI-V meters are point samples: between two SSB syllables a poll lands on
0 W and a perfect SWR, so a 150 W transmission read 0-10 W most of the time
and the SWR sat at 1.0. Power now decays like a needle and SWR holds its peak
then snaps to the live value — the same meterPeak the Yaesu and Kenwood
consoles already use. The readout column also widens so '180 W' stays on one
line.

internal/cat/icomserial.go

@@ -116,7 +116,13 @@ type IcomSerial struct {
 	//                       "alive but silent" tolerance below, which used to be
 	//                       unbounded and left the display frozen for ever
 	silentGrace time.Duration // current width of that tolerance (backs off, see ReadState)
-	dspLoaded   bool          // readDSP has run since the rig became responsive (loads all
+	// Needle inertia for the TX meters — the CI-V meters are point samples, and
+	// between two SSB syllables a poll lands on 0 W and a perfect SWR. See
+	// meterPeak (yaesu_panel.go): power decays like a needle, SWR holds then
+	// snaps back to the live truth.
+	powerPeak meterPeak
+	swrPeak   meterPeak
+	dspLoaded bool // readDSP has run since the rig became responsive (loads all
 	//                     the panel's set-once controls once the rig actually answers)
 	// When the console last asked for the DSP snapshot. The meters and the
 	// front-panel rotation are polled ONLY while something is displaying them:
@@ -456,12 +462,16 @@ func (b *IcomSerial) ReadState() (RigState, error) {
 		sm, _ = b.readMeter(civ.SubMeterS)
 		po, swr = 0, 0
 		if tx {
+			now := time.Now()
 			if v, ok := b.readMeter(civ.SubMeterPo); ok {
-				po = v
+				po = b.powerPeak.update(v, now)
 			}
 			if v, ok := b.readMeter(civ.SubMeterSWR); ok {
-				swr = v
+				swr = b.swrPeak.updateSnap(v, now)
 			}
+		} else {
+			// Cleared with the carrier, so the next transmission starts fresh.
+			b.powerPeak, b.swrPeak = meterPeak{}, meterPeak{}
 		}
 	}
 	b.dspMu.Lock()