Implement Substation: BLE-WS bridge with music-reactive e-stim

- Renamed from CoyoteBridge to Substation (namespace, classes, UI)
- BLE connection via WinRT with graceful disconnect handling
- WebSocket server (127.0.0.1:8765) with single-client, push events
  for BLE connect/disconnect transitions
- Operator strength limiter (clamp/scale modes, default 30)
- Tray icon with 3 states: neutral/active/hot (runtime-drawn voltage glyph)
- A/B strength gauges, hide-on-minimise to tray
- Music mode: MP3 decode + FFT analysis (NAudio + FftSharp), rhythm→ch A,
  melody→ch B, pre-analyzed with synced audio playback
- Test/Stop All work without BLE connected (dev mode)
- WS device-driving commands error when BLE not connected; ping/status/
  connect always work
- TreatWarningsAsErrors, LangVersion=latest
- .gitignore, README with full API docs + attribution

Program.cs

@@ -0,0 +1,24 @@
+namespace Substation;
+
+static class Program
+{
+    public const int Port = 8765;
+
+    [STAThread]
+    static void Main()
+    {
+        ApplicationConfiguration.Initialize();
+
+        using var device = new CoyoteDevice();
+        var state  = new State();
+        var server = new Server(device, state, Port);
+
+        device.StrengthChanged += (a, b) =>
+        {
+            state.ActualA = a;
+            state.ActualB = b;
+        };
+
+        Application.Run(new MainForm(device, state, server));
+    }
+}