Fix macOS quit: intercept applicationShouldTerminate: to allow real exit

GLFW's applicationShouldTerminate: converts all quit paths (Cmd+Q, dock,
menu bar) into window close requests and returns NSTerminateCancel, so our
close-to-hide intercept was hiding the window instead of letting the app exit.

Fix by implementing applicationShouldTerminate: in ReopenDelegate, setting a
darwinQuitting flag before forwarding to GLFW's delegate. The close intercept
checks this flag and calls Window.Close() instead of Hide() when quitting.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/mainwindow.go

@@ -185,7 +185,7 @@ func NewMainWindow(fyneApp fyne.App, appName, displayAppName, appVersion string,
 
 	m.Window.SetCloseIntercept(func() {
 		m.SaveWindowSettings()
-		if runtime.GOOS == "darwin" || (app.Config.Application.CloseToSystemTray && m.HaveSystemTray()) {
+		if (runtime.GOOS == "darwin" && !isRealQuit()) || (app.Config.Application.CloseToSystemTray && m.HaveSystemTray()) {
 			m.Window.Hide()
 		} else {
 			m.Window.Close()