fix: add scroll to entire gallery view

gallery/Main.qml

@@ -12,7 +12,8 @@ AppWindow {
     height: 480
     visible: true
     title: qsTr("flowy - gallery")
-
+    ScrollView {
+        anchors.fill: parent
         ColumnLayout {
             anchors.left: parent.left
             anchors.right: parent.right
@@ -157,3 +158,4 @@ AppWindow {
             }
         }
     }
+}