fix(conversation): topic chips after warmup + English chip copy

- Buffer topic_suggestions until chat UI attaches (uiOwner + callback); replay on attach
- build_topic_chips respects user language for label/text; router passes user_language

Co-authored-by: Cursor <cursoragent@cursor.com>

api/app/features/conversation/ws/router.py

@@ -235,6 +235,7 @@ async def websocket_endpoint(
                         memoir_state.current_stage,
                         empty_slots,
                         max_chips=settings.chat_topic_chips_max,
+                        language=user_language,
                     )
                     if not chips:
                         return