Add FFplay help feature and keyboard shortcut guide

Introduced a new "Help FFplay" section in the help menu to provide information about FFplay player keyboard shortcuts and actions.

handler/menu.go

@@ -88,14 +88,21 @@ func (h MenuHandler) getMenuHelp() *fyne.Menu {
 
 	gratitude := fyne.NewMenuItem(h.app.GetLocalizerService().GetMessage(&i18n.LocalizeConfig{
 		MessageID: "gratitude",
-	}), h.openGratitude)
+	}), h.menuView.Gratitude)
 	h.app.GetLocalizerService().AddChangeCallback("gratitude", func(text string) {
 		gratitude.Label = text
 	})
 
+	helpFFplay := fyne.NewMenuItem(h.app.GetLocalizerService().GetMessage(&i18n.LocalizeConfig{
+		MessageID: "helpFFplay",
+	}), h.menuView.HelpFFplay)
+	h.app.GetLocalizerService().AddChangeCallback("helpFFplay", func(text string) {
+		helpFFplay.Label = text
+	})
+
 	help := fyne.NewMenu(h.app.GetLocalizerService().GetMessage(&i18n.LocalizeConfig{
 		MessageID: "help",
-	}), about, gratitude)
+	}), helpFFplay, about, gratitude)
 	h.app.GetLocalizerService().AddChangeCallback("help", func(text string) {
 		help.Label = text
 		help.Refresh()
@@ -127,10 +134,6 @@ func (h MenuHandler) openAbout() {
 	h.menuView.About(ffmpeg, ffprobe, ffplay)
 }
 
-func (h MenuHandler) openGratitude() {
-	h.menuView.Gratitude()
-}
-
 func (h MenuHandler) LanguageSelection() {
 	h.localizerView.LanguageSelection(func(lang kernel.Lang) {
 		_, _ = h.localizerRepository.Save(lang.Code)