Remove music button and MP3 decode, keep live capture only

- Remove Music button, OnMusic/RunMusicAsync/StopMusic and all music fields
- MusicAnalyzer: remove Analyze, DecodeToMono, MusicPattern record;
  keep ExtractFeatures/MapPitchToPeriod/BuildWaveFrame/TickFeature (used by LiveCapture)
- Remove unused NAudio.Wave and System.Diagnostics imports from MainForm
- Fix LiveCapture overlap: sliding window with 50% overlap (was dropping every other frame)
- Buttons resized to 80px (Test/Live/Pattern/Stop All)

LiveCapture.cs

@@ -91,6 +91,7 @@ public class LiveCapture : IDisposable
         var window = new FftSharp.Windows.Hanning();
         var buffer = new double[MusicAnalyzer.WindowSize];
         var tf = new MusicAnalyzer.TickFeature();
+        double[]? overlap = null; // last HopSize samples from previous window
 
         while (_running)
         {
@@ -98,10 +99,23 @@ public class LiveCapture : IDisposable
 
             lock (_bufferLock)
             {
-                if (_sampleBuffer.Count >= MusicAnalyzer.WindowSize)
+                int needed = overlap != null ? MusicAnalyzer.HopSize : MusicAnalyzer.WindowSize;
+                if (_sampleBuffer.Count >= needed)
                 {
-                    for (int i = 0; i < MusicAnalyzer.WindowSize; i++)
-                        buffer[i] = _sampleBuffer.Dequeue();
+                    if (overlap != null)
+                    {
+                        Array.Copy(overlap, 0, buffer, 0, MusicAnalyzer.HopSize);
+                        for (int i = 0; i < MusicAnalyzer.HopSize; i++)
+                            buffer[MusicAnalyzer.HopSize + i] = _sampleBuffer.Dequeue();
+                    }
+                    else
+                    {
+                        for (int i = 0; i < MusicAnalyzer.WindowSize; i++)
+                            buffer[i] = _sampleBuffer.Dequeue();
+                    }
+                    // Save last HopSize samples for next window's overlap
+                    overlap = new double[MusicAnalyzer.HopSize];
+                    Array.Copy(buffer, MusicAnalyzer.HopSize, overlap, 0, MusicAnalyzer.HopSize);
                     windowData = buffer;
                 }
             }