Convert desktop to EchoType Bridge: pipe injection via TIP

- Add EchoType to TextInjectionMode enum (becomes default)
- Add WriteToEchoTypePipe(): write [UINT32 cch][WCHAR text] to
  \.\pipe\EchoType\pid_<PID> via NamedPipeClientStream
- InsertText(): route to EchoType pipe when mode is EchoType
- TrayApplicationContext: add 'EchoType (recommended)' to input mode menu
- Update tray branding: 'EchoType Bridge' in tooltips and balloon tips
- AppLogger: log to %LocalAppData%\EchoType\bridge.log

The bridge keeps WebSocket server + UDP discovery + audio control
unchanged. Text injection now goes through the EchoType TIP's
composition-commit mechanism for atomic insertion, falling back to
clipboard and SendInput as secondary options.

Co-Authored-By: Claude <noreply@anthropic.com>

WirelessTextSyncer.Windows/Services/KeyboardInjectionService.cs

@@ -1,9 +1,11 @@
-namespace WirelessTextSyncer.Windows.Services;
-
+using System.IO.Pipes;
 using System.Runtime.InteropServices;
 
+namespace WirelessTextSyncer.Windows.Services;
+
 public enum TextInjectionMode
 {
+    EchoType,
     ClipboardPaste,
     SendInputTyping
 }
@@ -22,7 +24,7 @@ public sealed class KeyboardInjectionService : IKeyboardInjectionService
     private const ushort VirtualKeyV = 0x56;
     private static readonly IntPtr EnglishKeyboardLayout = LoadKeyboardLayout("00000409", KlfActivate);
 
-    public TextInjectionMode Mode { get; set; } = TextInjectionMode.ClipboardPaste;
+    public TextInjectionMode Mode { get; set; } = TextInjectionMode.EchoType;
 
     public void InsertText(string text)
     {
@@ -32,6 +34,12 @@ public sealed class KeyboardInjectionService : IKeyboardInjectionService
         }
 
         AppLogger.Info($"Inserting text length: {text.Length}. Mode: {Mode}.");
+        if (Mode == TextInjectionMode.EchoType)
+        {
+            WriteToEchoTypePipe(text);
+            return;
+        }
+
         if (Mode == TextInjectionMode.SendInputTyping)
         {
             TypeTextWithSendInput(text);
@@ -41,6 +49,50 @@ public sealed class KeyboardInjectionService : IKeyboardInjectionService
         PasteTextViaClipboard(text);
     }
 
+    private static void WriteToEchoTypePipe(string text)
+    {
+        var fgWindow = GetForegroundWindow();
+        if (fgWindow == IntPtr.Zero)
+        {
+            AppLogger.Error("EchoType pipe: no foreground window.");
+            return;
+        }
+
+        GetWindowThreadProcessId(fgWindow, out var pid);
+        if (pid == 0)
+        {
+            AppLogger.Error("EchoType pipe: failed to get PID.");
+            return;
+        }
+
+        var pipeName = $@"EchoType\pid_{pid}";
+
+        try
+        {
+            using var pipe = new NamedPipeClientStream(".", pipeName, PipeDirection.Out);
+            pipe.Connect(timeout: 2000);
+
+            var utf16 = System.Text.Encoding.Unicode.GetBytes(text);
+            var cch = (uint)text.Length;
+            var header = BitConverter.GetBytes(cch);
+
+            pipe.Write(header, 0, 4);
+            pipe.Write(utf16, 0, utf16.Length);
+            pipe.Flush();
+
+            AppLogger.Info($"EchoType pipe: sent {cch} chars to PID {pid}.");
+        }
+        catch (TimeoutException)
+        {
+            AppLogger.Error(
+                $"EchoType pipe: connection timeout for PID {pid}. Is EchoType the active IME in that app?");
+        }
+        catch (Exception ex)
+        {
+            AppLogger.Error($"EchoType pipe write failed for PID {pid}.", ex);
+        }
+    }
+
     private static void TypeTextWithSendInput(string text)
     {
         AppLogger.Info($"Falling back to SendInput text length: {text.Length}");