Add Random button (pink noise generator) with counterphase channels

- Voss-McCartney pink noise (1/f spectrum) for intensity and frequency
- Separate state per channel, channel B inverted for counterphase
- Intensity capped at 80 for comfort, frequency spans full 10-1000ms range
- Runs continuously, stopped via Stop All or switching modes
- 5th button (68px), all buttons resized to fit one row

MainForm.cs

@@ -52,11 +52,13 @@ public class MainForm : Form
 
     readonly Button _btnLive;
     readonly Button _btnPattern;
+    readonly Button _btnRandom;
     readonly Label _lblTrack;
     readonly Label _lblAudioDev;
     readonly ComboBox _cboAudioDev;
     bool _isLiveRunning;
     bool _isPatternRunning;
+    bool _isRandomRunning;
     LiveCapture? _liveCapture;
 
     public MainForm(CoyoteDevice device, State state, Server server)
@@ -123,31 +125,39 @@ public class MainForm : Form
         {
             Text = "Test",
             Location = new Point(16, 96),
-            Size = new Size(80, 32)
+            Size = new Size(68, 32)
         };
         _btnTest.Click += OnTest;
 
         _btnLive = new Button
         {
             Text = "Live",
-            Location = new Point(104, 96),
-            Size = new Size(80, 32)
+            Location = new Point(92, 96),
+            Size = new Size(68, 32)
         };
         _btnLive.Click += OnLive;
 
         _btnPattern = new Button
         {
             Text = "Pattern",
-            Location = new Point(192, 96),
-            Size = new Size(80, 32)
+            Location = new Point(168, 96),
+            Size = new Size(68, 32)
         };
         _btnPattern.Click += OnPattern;
 
+        _btnRandom = new Button
+        {
+            Text = "Random",
+            Location = new Point(244, 96),
+            Size = new Size(68, 32)
+        };
+        _btnRandom.Click += OnRandom;
+
         _btnStop = new Button
         {
             Text = "Stop All",
-            Location = new Point(280, 96),
-            Size = new Size(80, 32)
+            Location = new Point(320, 96),
+            Size = new Size(76, 32)
         };
         _btnStop.Click += OnStop;
 
@@ -350,7 +360,7 @@ public class MainForm : Form
         };
         OnAmpChanged(null, EventArgs.Empty);
 
-        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _chkSwap, _btnTest, _btnLive, _btnPattern, _btnStop, _lblAudioDev, _cboAudioDev, _lblTrack, _lblSendA, _heatA, _lblSendB, _heatB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimitA, _limitBarA, _lblLimitValA, _chkScaleA, _lblLimitB, _limitBarB, _lblLimitValB, _chkScaleB, _lblAmpA, _ampBarA, _lblAmpValA, _lblAmpB, _ampBarB, _lblAmpValB });
+        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _chkSwap, _btnTest, _btnLive, _btnPattern, _btnRandom, _btnStop, _lblAudioDev, _cboAudioDev, _lblTrack, _lblSendA, _heatA, _lblSendB, _heatB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimitA, _limitBarA, _lblLimitValA, _chkScaleA, _lblLimitB, _limitBarB, _lblLimitValB, _chkScaleB, _lblAmpA, _ampBarA, _lblAmpValA, _lblAmpB, _ampBarB, _lblAmpValB });
 
         // Tray icon — three cached variants: neutral=gray, active=gold, hot=red-orange
         _iconNeutral = CreateVoltageIcon(Color.Gray);
@@ -520,10 +530,11 @@ public class MainForm : Form
 
     void RefreshButtonStates()
     {
-        bool busy = IsTestRunning || _isLiveRunning || _isPatternRunning;
+        bool busy = IsTestRunning || _isLiveRunning || _isPatternRunning || _isRandomRunning;
         _btnTest.Enabled = !_server.HasClient && !busy;
         _btnLive.Enabled = !_server.HasClient && !busy;
         _btnPattern.Enabled = !_server.HasClient && !busy;
+        _btnRandom.Enabled = !_server.HasClient && !busy;
         _btnStop.Enabled = true;
     }
 
@@ -539,6 +550,10 @@ public class MainForm : Form
         {
             _lblTrack.Text = $"Pattern: {_patternName}";
         }
+        else if (_isRandomRunning)
+        {
+            _lblTrack.Text = "Random noise";
+        }
 
         UpdateTrayIcon();
     }
@@ -605,6 +620,7 @@ public class MainForm : Form
     {
         StopLive();
         StopPattern();
+        StopRandom();
         _state.SetStrength('A', 0);
         _state.SetStrength('B', 0);
         _state.Stop('A');
@@ -772,6 +788,90 @@ public class MainForm : Form
         }
     }
 
+    CancellationTokenSource? _randomCts;
+
+    void OnRandom(object? sender, EventArgs e)
+    {
+        if (_isRandomRunning || _server.HasClient) return;
+
+        _isRandomRunning = true;
+        _btnRandom.Enabled = false;
+        _lblTrack.Text = "Random noise";
+
+        _state.SetStrength('A', 60);
+        _state.SetStrength('B', 60);
+        _state.Stop('A');
+        _state.Stop('B');
+
+        _randomCts = new CancellationTokenSource();
+        Task.Run(() => RunRandomAsync(_randomCts.Token));
+    }
+
+    async Task RunRandomAsync(CancellationToken ct)
+    {
+        // Pink noise via Voss-McCartney algorithm (1/f spectrum)
+        // Separate state per channel, B inverted for counterphase
+        var rng = new Random();
+        int octaves = 8;
+        var rowsA = new double[octaves];
+        var rowsB = new double[octaves];
+        double pinkA = 0, pinkB = 0;
+
+        while (!ct.IsCancellationRequested && _isRandomRunning)
+        {
+            // Channel A
+            int updateA = rng.Next(octaves);
+            rowsA[updateA] = rng.NextDouble() * 2 - 1;
+            pinkA = 0;
+            for (int i = 0; i < octaves; i++) pinkA += rowsA[i];
+            pinkA /= octaves;
+
+            // Channel B (independent state, inverted for counterphase)
+            int updateB = rng.Next(octaves);
+            rowsB[updateB] = rng.NextDouble() * 2 - 1;
+            pinkB = 0;
+            for (int i = 0; i < octaves; i++) pinkB += rowsB[i];
+            pinkB /= octaves;
+            pinkB = -pinkB; // counterphase
+
+            // Map pink noise (-1..1) to intensity (0..80, capped for comfort)
+            int intA = (int)Math.Clamp((pinkA + 1) * 40, 0, 80);
+            int intB = (int)Math.Clamp((pinkB + 1) * 40, 0, 80);
+
+            // Random frequency: map pink noise to period (10-1000ms)
+            int freqMsA = (int)Math.Clamp((pinkA + 1) * 500, 10, 1000);
+            int freqMsB = (int)Math.Clamp((pinkB + 1) * 500, 10, 1000);
+
+            var frameA = new WaveFrame(
+                Freq.Compress4(new[] { freqMsA, freqMsA, freqMsA, freqMsA }),
+                Intensity.Clamp4(new[] { intA, intA, intA, intA }));
+            var frameB = new WaveFrame(
+                Freq.Compress4(new[] { freqMsB, freqMsB, freqMsB, freqMsB }),
+                Intensity.Clamp4(new[] { intB, intB, intB, intB }));
+
+            _state.EnqueueStream('A', new[] { frameA });
+            _state.EnqueueStream('B', new[] { frameB });
+
+            try { await Task.Delay(100, ct); } catch (OperationCanceledException) { break; }
+        }
+    }
+
+    void StopRandom()
+    {
+        _randomCts?.Cancel();
+        _randomCts = null;
+
+        if (_isRandomRunning)
+        {
+            _isRandomRunning = false;
+            if (!IsDisposed)
+            {
+                _lblTrack.Text = "";
+                RefreshButtonStates();
+            }
+        }
+    }
+
     string ShowInputDialog(string prompt, string title)
     {
         using var dlg = new Form