gui: wrap prompt input in ScrollView for scrollable multi-line text area

- TextArea grows from 5 rows up to 200px as content increases
- Auto-scrolls to bottom on text change
- Uses Math.min(contentHeight, max) to avoid unnecessary space

gui/main.qml

@@ -444,13 +444,22 @@ ApplicationWindow {
                 Layout.margins: 6
                 spacing: 4
 
+                ScrollView {
+                    Layout.fillWidth: true
+                    Layout.maximumHeight: 200
+                    Layout.preferredHeight: Math.min(promptInput.contentHeight + 16, 200)
+                    clip: true
+
                     TextArea {
                         id: promptInput
                         Layout.fillWidth: true
-                    Layout.preferredHeight: font.pointSize * 5 + 16
                         placeholderText: ollie.activeSessionId ? "Message..." : "No session"
                         enabled: ollie.activeSessionId !== ""
                         wrapMode: TextEdit.Wrap
+                        onTextChanged: {
+                            // Auto-scroll to bottom as content grows
+                            textCursor.position = text.length
+                        }
                         Keys.onReturnPressed: {
                             if (event.modifiers & Qt.ShiftModifier) {
                                 event.accepted = false
@@ -467,3 +476,4 @@ ApplicationWindow {
             }
         }
     }
+}