Add xToys pattern import via URL paste

- XToysPattern.cs: fetch pattern from xtoys.app API (one call), parse
  script-v3 JSON, resolve slider defaults, evaluate sine/straight steps
  to WaveFrames at 100ms resolution
- Frequency mapping: 0%=1000ms deep, 100%=10ms buzzy
- MainForm: Pattern button + input dialog, continuously enqueues pattern
  frames as a loop, Stop All cancels
- Fix: handle JSON values that are numbers vs strings (end/start fields)
- NOTES.md: xToys slider parameter intel + frequency mapping docs

MainForm.cs

@@ -50,11 +50,13 @@ public class MainForm : Form
 
     readonly Button _btnMusic;
     readonly Button _btnLive;
+    readonly Button _btnPattern;
     readonly Label _lblTrack;
     readonly Label _lblAudioDev;
     readonly ComboBox _cboAudioDev;
     bool _isMusicRunning;
     bool _isLiveRunning;
+    bool _isPatternRunning;
     WaveOutEvent? _audioOut;
     Stopwatch? _musicStopwatch;
     LiveCapture? _liveCapture;
@@ -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;
 
         _btnMusic = new Button
         {
             Text = "Music",
-            Location = new Point(104, 96),
-            Size = new Size(80, 32)
+            Location = new Point(92, 96),
+            Size = new Size(68, 32)
         };
         _btnMusic.Click += OnMusic;
 
         _btnLive = new Button
         {
             Text = "Live",
-            Location = new Point(192, 96),
-            Size = new Size(80, 32)
+            Location = new Point(168, 96),
+            Size = new Size(68, 32)
         };
         _btnLive.Click += OnLive;
 
+        _btnPattern = new Button
+        {
+            Text = "Pattern",
+            Location = new Point(244, 96),
+            Size = new Size(68, 32)
+        };
+        _btnPattern.Click += OnPattern;
+
         _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;
 
@@ -297,7 +307,7 @@ public class MainForm : Form
         _chkScaleB.CheckedChanged += OnLimitChanged;
         OnLimitChanged(null, EventArgs.Empty);
 
-        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _chkSwap, _btnTest, _btnMusic, _btnLive, _btnStop, _lblAudioDev, _cboAudioDev, _lblTrack, _lblSendA, _heatA, _lblSendB, _heatB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimitA, _limitBarA, _lblLimitValA, _chkScaleA, _lblLimitB, _limitBarB, _lblLimitValB, _chkScaleB });
+        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _chkSwap, _btnTest, _btnMusic, _btnLive, _btnPattern, _btnStop, _lblAudioDev, _cboAudioDev, _lblTrack, _lblSendA, _heatA, _lblSendB, _heatB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimitA, _limitBarA, _lblLimitValA, _chkScaleA, _lblLimitB, _limitBarB, _lblLimitValB, _chkScaleB });
 
         // Tray icon — three cached variants: neutral=gray, active=gold, hot=red-orange
         _iconNeutral = CreateVoltageIcon(Color.Gray);
@@ -465,9 +475,11 @@ public class MainForm : Form
 
     void RefreshButtonStates()
     {
-        _btnTest.Enabled = !_server.HasClient && !IsTestRunning && !_isMusicRunning && !_isLiveRunning;
-        _btnMusic.Enabled = !_server.HasClient && !_isMusicRunning && !IsTestRunning && !_isLiveRunning;
-        _btnLive.Enabled = !_server.HasClient && !_isLiveRunning && !IsTestRunning && !_isMusicRunning;
+        bool busy = IsTestRunning || _isMusicRunning || _isLiveRunning || _isPatternRunning;
+        _btnTest.Enabled = !_server.HasClient && !busy;
+        _btnMusic.Enabled = !_server.HasClient && !busy;
+        _btnLive.Enabled = !_server.HasClient && !busy;
+        _btnPattern.Enabled = !_server.HasClient && !busy;
         _btnStop.Enabled = true;
     }
 
@@ -484,6 +496,10 @@ public class MainForm : Form
         {
             _lblTrack.Text = "Live capture";
         }
+        else if (_isPatternRunning)
+        {
+            _lblTrack.Text = $"Pattern: {_patternName}";
+        }
 
         UpdateTrayIcon();
     }
@@ -550,6 +566,7 @@ public class MainForm : Form
     {
         StopMusic();
         StopLive();
+        StopPattern();
         _state.SetStrength('A', 0);
         _state.SetStrength('B', 0);
         _state.Stop('A');
@@ -732,6 +749,102 @@ public class MainForm : Form
         }
     }
 
+    string _patternName = "";
+    CancellationTokenSource? _patternCts;
+
+    void OnPattern(object? sender, EventArgs e)
+    {
+        if (_isPatternRunning || _server.HasClient) return;
+
+        var url = ShowInputDialog("Paste xToys pattern URL:", "Pattern Import");
+        if (string.IsNullOrWhiteSpace(url)) return;
+
+        _isPatternRunning = true;
+        _btnPattern.Enabled = false;
+        _lblTrack.Text = "Loading pattern...";
+
+        _patternCts = new CancellationTokenSource();
+        Task.Run(() => RunPatternAsync(url, _patternCts.Token));
+    }
+
+    async Task RunPatternAsync(string url, CancellationToken ct)
+    {
+        XToysPattern? pattern = null;
+        try
+        {
+            pattern = await XToysPatternImporter.ImportAsync(url);
+        }
+        catch (Exception ex)
+        {
+            BeginInvoke(() =>
+            {
+                _lblTrack.Text = $"Pattern failed: {ex.Message?.Split('\n')[0]}";
+                _isPatternRunning = false;
+                RefreshButtonStates();
+            });
+            return;
+        }
+
+        _patternName = pattern.Name;
+
+        _state.SetStrength('A', 60);
+        _state.SetStrength('B', 60);
+        _state.Stop('A');
+        _state.Stop('B');
+
+        BeginInvoke(() => _lblTrack.Text = $"Pattern: {_patternName}");
+
+        // Continuously enqueue pattern frames at 100ms per frame
+        int idx = 0;
+        while (!ct.IsCancellationRequested && _isPatternRunning)
+        {
+            var frameA = pattern.ChannelA[idx];
+            var frameB = pattern.ChannelB[idx];
+            _state.EnqueueStream('A', new[] { frameA });
+            _state.EnqueueStream('B', new[] { frameB });
+            idx = (idx + 1) % pattern.ChannelA.Count;
+
+            try { await Task.Delay(100, ct); } catch (OperationCanceledException) { break; }
+        }
+    }
+
+    void StopPattern()
+    {
+        _patternCts?.Cancel();
+        _patternCts = null;
+
+        if (_isPatternRunning)
+        {
+            _isPatternRunning = false;
+            if (!IsDisposed)
+            {
+                _lblTrack.Text = "";
+                RefreshButtonStates();
+            }
+        }
+    }
+
+    string ShowInputDialog(string prompt, string title)
+    {
+        using var dlg = new Form
+        {
+            Text = title,
+            FormBorderStyle = FormBorderStyle.FixedDialog,
+            ClientSize = new Size(380, 100),
+            StartPosition = FormStartPosition.CenterParent,
+            MaximizeBox = false,
+            MinimizeBox = false
+        };
+        var lbl = new Label { Text = prompt, Location = new Point(12, 12), Size = new Size(356, 20) };
+        var txt = new TextBox { Location = new Point(12, 36), Size = new Size(356, 22) };
+        var ok = new Button { Text = "OK", DialogResult = DialogResult.OK, Location = new Point(200, 66), Size = new Size(80, 24) };
+        var cancel = new Button { Text = "Cancel", DialogResult = DialogResult.Cancel, Location = new Point(288, 66), Size = new Size(80, 24) };
+        dlg.Controls.AddRange(new Control[] { lbl, txt, ok, cancel });
+        dlg.AcceptButton = ok;
+        dlg.CancelButton = cancel;
+        return dlg.ShowDialog(this) == DialogResult.OK ? txt.Text.Trim() : "";
+    }
+
     void UpdateTrayIcon()
     {
         var newState = _state.IsSignaling ? "hot"