feat: scroll to bottom on new user message

when the user sends a new message, and if the user is at an older position
in the timeline, then neochat should automatically scroll to the latest message and mark all the messages as read

imports/NeoChat/Page/RoomPage.qml

@@ -567,8 +567,7 @@ Kirigami.ScrollablePage {
                     if (currentRoom && currentRoom.hasUnreadMessages) {
                         goToEvent(currentRoom.readMarkerEventId)
                     } else {
-                        currentRoom.markAllMessagesAsRead()
-                        messageListView.positionViewAtBeginning()
+                        goToLastMessage();
                     }
                 }
                 icon.name: currentRoom && currentRoom.hasUnreadMessages ? "go-up" : "go-down"
@@ -654,6 +653,11 @@ Kirigami.ScrollablePage {
     footer: ChatBox {
         id: chatBox
         visible: !invitation.visible && !(messageListView.count === 0 && !currentRoom.allHistoryLoaded)
+        onMessageSent: {
+            if (!messageListView.atYEnd) {
+                goToLastMessage();
+            }
+        }
     }
 
     background: FancyEffectsContainer {
@@ -690,6 +694,12 @@ Kirigami.ScrollablePage {
         }
     }
 
+    function goToLastMessage() {
+        currentRoom.markAllMessagesAsRead()
+        // scroll to the very end, i.e to messageListView.YEnd
+        messageListView.positionViewAtIndex(0, ListView.End)
+    }
+
     function goToEvent(eventID) {
         messageListView.positionViewAtIndex(eventToIndex(eventID), ListView.Contain)
     }