refactor(mobile): stack only through merging from timeline (#4598)

* mobile: remove stack selection page

* mobile: require at-least 2 assets to stack

* mobile: sort stack children by fileCreatedAt

---------

Co-authored-by: shalong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>

mobile/lib/modules/home/ui/control_bottom_app_bar.dart

@@ -94,7 +94,7 @@ class ControlBottomAppBar extends ConsumerWidget {
                 }
               : null,
         ),
-        if (!hasLocal)
+        if (!hasLocal && selectionAssetState.selectedCount > 1)
           ControlBoxButton(
             iconData: Icons.filter_none_rounded,
             label: "control_bottom_app_bar_stack".tr(),