fix(CreateChat):Fix CreateChatView clipping in portrait layout

Applies a conditional left anchor to the `CreateChatView` loader to ensure proper width allocation in portrait mode.

Prevents the view from being cut off on the left while keeping the previous layout behavior in landscape.

Fixes #19062

Author: noeliaSD

ui/app/mainui/AppMain.qml

@@ -2394,6 +2394,7 @@ Item {
             Loader {
                 id: createChatView
 
+                readonly property bool isPortraitMode: appMain.width < Theme.portraitBreakpoint.width
                 property bool opened: false
                 readonly property real defaultWidth: parent.width - Constants.chatSectionLeftColumnWidth -
                          anchors.rightMargin - anchors.leftMargin
@@ -2402,8 +2403,10 @@ Item {
                 anchors.top: parent.top
                 anchors.topMargin: 8
                 anchors.rightMargin: 8
+                anchors.leftMargin: 8
                 anchors.bottom: parent.bottom
                 anchors.right: parent.right
+                anchors.left: isPortraitMode ? parent.left : undefined
 
                 sourceComponent: CreateChatView {
                     width: Math.min(Math.max(implicitWidth, createChatView.defaultWidth), createChatView.parent.width)