fix(ui): keep message-part tool output auto-scroll synced (#567)

## Summary
- Pass MessagePart render notifications into ToolCall as
onContentRendered.
- Ensures streaming bash output rendered through the generic MessagePart
path notifies the outer VirtualFollowList when content grows.

## Validation
- npm run typecheck --workspace @codenomad/ui

packages/ui/src/components/message-part.tsx

@@ -277,6 +277,7 @@ export default function MessagePart(props: MessagePartProps) {
             toolCallId={props.part?.id}
             instanceId={props.instanceId}
             sessionId={props.sessionId}
+            onContentRendered={props.onRendered}
           />
         </Suspense>
       </Match>