feat: add desktop system tray support (#120)

ui/flutter/windows/runner/main.cpp

@@ -7,6 +7,12 @@
 
 int APIENTRY wWinMain(_In_ HINSTANCE instance, _In_opt_ HINSTANCE prev,
                       _In_ wchar_t *command_line, _In_ int show_command) {
+  HWND hwnd = ::FindWindow(L"FLUTTER_RUNNER_WIN32_WINDOW", L"gopeed");
+  if (hwnd != NULL) {
+    ::ShowWindow(hwnd, SW_NORMAL);
+    ::SetForegroundWindow(hwnd);
+    return EXIT_FAILURE;
+  }
   // Attach to console when present (e.g., 'flutter run') or create a
   // new console when running with a debugger.
   if (!::AttachConsole(ATTACH_PARENT_PROCESS) && ::IsDebuggerPresent()) {