清理策划模式提交后的聊天草稿

规划 V2 提交时同步清空资源引用和 canonical content，避免切回 DirectProject 后复用旧输入。

apps/ai-game-creator-shell/src/App.tsx

@@ -11828,6 +11828,8 @@ export function App({
       supervisorChatShouldFollowLatestRef.current = true;
       const clientTurnId = createAgentChatRunId('planning-v2-turn');
       setChatInput('');
+      setChatReferences([]);
+      setChatContent([]);
       setMessages((current) => [
         ...current,
         {