UI: Don't recreate a screen's views while a popup is on top of it

Popups are transparent, so the screen under one still renders, and
render() ran DoRecreateViews(). A RecreateViews() on that screen (a
resize or rotation on DisplayLayoutScreen or TouchControlLayoutScreen,
MainScreen on RECENT_FILES_CHANGED from the recent-files thread, the
achievements login finishing) then deleted the choice that opened the
popup. Closing the popup wrote through it and called its handlers.

Leave the old views in place until the screen is back on top, where
update() recreates them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Common/UI/ScreenManager.cpp

@@ -393,6 +393,15 @@ void ScreenManager::finishDialog(Screen *dialog, DialogResult result) {
 	dialogResult_ = result;
 }
 
+bool ScreenManager::HasScreenAbove(const Screen *screen) const {
+	for (size_t i = 0; i + 1 < stack_.size(); ++i) {
+		if (stack_[i].screen == screen) {
+			return true;
+		}
+	}
+	return false;
+}
+
 Screen *ScreenManager::dialogParent(const Screen *dialog) const {
 	for (size_t i = 1; i < stack_.size(); ++i) {
 		if (stack_[i].screen == dialog) {