Fix Send gauges showing intensity, zero when idle

- Send gauges now show waveform intensity (0-100) not strength ceiling
- State.LastIntensityA/B tracks average intensity per tick
- Zero when no pattern/stream active (was 25 due to IntensityOff 101 sentinel)
- Recv gauges unchanged (device-reported strength 0-200)

State.cs

@@ -17,6 +17,7 @@ public class State
 
     public int ActualA, ActualB;
     public int LastSentA, LastSentB;
+    public int LastIntensityA, LastIntensityB;
 
     public int MaxStrength = 200;
     public LimitMode LimitMode = LimitMode.Clamp;
@@ -105,9 +106,14 @@ public class State
             DirtyA = false;
             DirtyB = false;
 
+            bool hasA = !StreamA.IsEmpty || (LoopFreqA != null && LoopIntA != null);
+            bool hasB = !StreamB.IsEmpty || (LoopFreqB != null && LoopIntB != null);
             var (freqA, intA) = PopWave(StreamA, LoopFreqA, LoopIntA);
             var (freqB, intB) = PopWave(StreamB, LoopFreqB, LoopIntB);
 
+            LastIntensityA = hasA ? (intA[0] + intA[1] + intA[2] + intA[3]) / 4 : 0;
+            LastIntensityB = hasB ? (intB[0] + intB[1] + intB[2] + intB[3]) / 4 : 0;
+
             return (modeA, valA, modeB, valB, freqA, intA, freqB, intB);
         }
     }