模型选择保存期间禁用选项，避免并发选择竞态

针对 review 提出的 P2：保存 select_game_creator_model 期间重新打开菜单再选一次会挂起两条 invoke，完成第一条即解锁发送导致显示/配置错乱

保存期间禁用下拉选项（可查看菜单，不可再选），保存完成后恢复；补充并发回归测试

apps/ai-game-creator-shell/src/features/project-workspace/ConversationModelSelect.tsx

@@ -160,6 +160,7 @@ export function ConversationModelSelect({
               type="button"
               role="option"
               aria-selected={model.id === selected}
+              disabled={disabled || busy}
               onClick={() => {
                 setOpen(false);
                 void select(model.id);

apps/ai-game-creator-shell/tests/conversationModelSelect.test.tsx

@@ -137,3 +137,42 @@ test('marks the default model in the menu', async () => {
   const fastOption = screen.getByRole('option', { name: '快速' });
   expect(within(fastOption).queryByText('默认')).toBeNull();
 });
+
+test('keeps model options disabled while a selection save is in flight', async () => {
+  let resolveSave: ((value: unknown) => void) | undefined;
+  invoke.mockImplementation(async (command, input) => {
+    if (command === 'select_game_creator_model') {
+      return new Promise((resolve) => {
+        resolveSave = resolve;
+      });
+    }
+    return { config: { selectedModelId: 'quality' } };
+  });
+  const onReady = vi.fn();
+  render(<ConversationModelSelect disabled={false} onReady={onReady} />);
+  await screen.findByRole('button', { name: '对话模型' });
+  await waitFor(() => expect(onReady).toHaveBeenLastCalledWith(true));
+
+  fireEvent.click(screen.getByRole('button', { name: '对话模型' }));
+  await screen.findByRole('option', { name: '快速' });
+  fireEvent.click(screen.getByRole('option', { name: '快速' }));
+
+  // 保存期间重新打开菜单：可以查看，但选项应禁用，避免并发选择。
+  fireEvent.click(screen.getByRole('button', { name: '对话模型' }));
+  expect(screen.getByRole('option', { name: '快速' })).toHaveProperty(
+    'disabled',
+    true,
+  );
+  expect(screen.getByRole('option', { name: /高质量/ })).toHaveProperty(
+    'disabled',
+    true,
+  );
+  expect(onReady).toHaveBeenLastCalledWith(false);
+
+  resolveSave?.({ config: { selectedModelId: 'fast' } });
+  await waitFor(() => expect(onReady).toHaveBeenLastCalledWith(true));
+  expect(screen.getByRole('option', { name: '快速' })).toHaveProperty(
+    'disabled',
+    false,
+  );
+});