Push to PageRow on mobile too

This fixes some glitches during animation, which had the background
disappearing when the pop animation was running,
and now uses always the pagerow for viewing the room.

This depends from the new PageRow animation on mobile,
https://invent.kde.org/frameworks/kirigami/-/merge_requests/1925
which makes all applications coherent with an application which
looks a bit more like the one on most android apps.

Also, the swipe back gesture now will work there too

src/app/qml/Main.qml

@@ -100,7 +100,8 @@ Kirigami.ApplicationWindow {
 
         function onCurrentRoomChanged() {
             if (RoomManager.currentRoom && root.pageStack.depth <= 1 && root.initialized && Kirigami.Settings.isMobile) {
-                let roomPage = root.pageStack.layers.push(Qt.createComponent('org.kde.neochat', 'RoomPage'));
+                let roomPage = pageStack.push(Qt.createComponent('org.kde.neochat', 'RoomPage'));
+                roomPage.forceActiveFocus();
                 roomPage.backRequested.connect(event => {
                     RoomManager.clearCurrentRoom();
                 });

src/app/qml/RoomPage.qml

@@ -252,12 +252,6 @@ Kirigami.Page {
         }
     }
 
-    background: Rectangle {
-        Kirigami.Theme.colorSet: Kirigami.Theme.View
-        Kirigami.Theme.inherit: false
-        color: NeoChatConfig.compactLayout ? Kirigami.Theme.backgroundColor : "transparent"
-    }
-
     footer: Loader {
         id: chatBarLoader
         height: active ? (item as ChatBar).implicitHeight : 0