gui: fix scrolling - use contentHeight not timer

Replace timer-based scroll hack with event-driven approach:
- onContentHeightChanged triggers scroll when content grows
- onMovementEnded detects when user scrolled away from bottom

Scrolling is now driven by actual content changes, not arbitrary delays.

gui/main.qml

@@ -93,17 +93,6 @@ ApplicationWindow {
     // Sidebar visibility
     property bool sidebarVisible: true
 
-    // Deferred scroll timer — fires once after model changes settle
-    Timer {
-        id: scrollTimer
-        interval: 16  // ~1 frame at 60fps, allows layout to settle
-        repeat: false
-        onTriggered: {
-            if (chatView.shouldAutoScroll)
-                chatView.positionViewAtEnd()
-        }
-    }
-
     // Session ID to kill — set on right-click, consumed by context menu
     property string killTargetSessionId: ""
     // Target session for "New Agent" dialog
@@ -478,7 +467,6 @@ ApplicationWindow {
                 chatModel.trimFront(20)
             }
         }
-        scrollTimer.start()
         // Ensure we have the latest session list
         ollie.refreshSessions()
         buildSessionTree()
@@ -496,7 +484,6 @@ ApplicationWindow {
                     chatModel.trimFront(20)
                 }
             }
-            scrollTimer.start()
         }
         function onActiveAgentIdChanged() {
             chatModel.reset()
@@ -508,7 +495,6 @@ ApplicationWindow {
                     chatModel.trimFront(20)
                 }
             }
-            scrollTimer.start()
         }
     }
 
@@ -897,40 +883,26 @@ ApplicationWindow {
                     boundsBehavior: Flickable.StopAtBounds
                     visible: ollie.daemonConnected && ollie.activeAgentId !== ""
 
-                        // Auto-scroll when near bottom (within ~50px or at end)
-                        // Reset to true on new blocks, user can scroll up to disable
-                        property bool shouldAutoScroll: true
-                        readonly property bool nearBottom: contentHeight - contentY - height < 50
+                    // Auto-scroll state: true = follow new content, false = user scrolled up
+                    property bool shouldAutoScroll: true
 
-                        onContentYChanged: {
-                            // User scrolled up - disable auto-scroll
-                            // User scrolled to bottom - re-enable
-                            if (dragging || flicking) {
-                                shouldAutoScroll = nearBottom || atYEnd
-                            }
-                        }
-                        
-                        onCountChanged: {
-                            // New block added - always scroll if we were following
-                            if (count > 0) {
-                                if (shouldAutoScroll)
-                                    scrollTimer.start()
-                            }
+                    onContentHeightChanged: {
+                        // Content grew — scroll to end if we're following
+                        if (shouldAutoScroll && contentHeight > height) {
+                            positionViewAtEnd()
                         }
+                    }
 
-                        Connections {
-                            target: chatModel
-                            function onDataChanged() {
-                                // Content updated (streaming) - scroll if following
-                                if (chatView.shouldAutoScroll && chatView.count > 0)
-                                    scrollTimer.start()
-                            }
-                        }
+                    onMovementEnded: {
+                        // User finished scrolling — update auto-scroll based on position
+                        // atYEnd is true when scrolled to bottom
+                        shouldAutoScroll = atYEnd
+                    }
 
-                        delegate: ChatBlockDelegate {
-                            width: chatView.width - 8
-                            parentListView: chatView
-                        }
+                    delegate: ChatBlockDelegate {
+                        width: chatView.width - 8
+                        parentListView: chatView
+                    }
                 }
                 
             }