tui: clarify queue replay stop comment

Explain that the busy-path Stop return in dispatch_command() only matters for live dispatch because queued replay never reaches that branch.

Co-authored-by: Codex <noreply@openai.com>

codex-rs/tui/src/chatwidget.rs

@@ -4332,7 +4332,8 @@ impl ChatWidget {
             self.queue_user_message(format!("/{}", cmd.command()).into());
             // This busy-path queueing only happens for live command dispatch. Queued replay
             // executes slash drafts only while idle, and handle_serialized_slash_command() queues
-            // instead of dispatching when a task is already running.
+            // instead of dispatching when a task is already running, so this Stop result is not
+            // material to replay behavior.
             return QueueReplayControl::Stop;
         }
         match cmd {