TUI support for buffer experience (#29919)

codex-rs/tui/src/chatwidget/constructor.rs

@@ -154,6 +154,7 @@ impl ChatWidget {
             last_unified_wait: None,
             unified_exec_wait_streak: None,
             turn_lifecycle: TurnLifecycleState::new(prevent_idle_sleep),
+            safety_buffering: SafetyBufferingState::default(),
             task_complete_pending: false,
             unified_exec_processes: Vec::new(),
             mcp_startup_status: None,