[Bug]: flutter_boost 4.6.5 卡死

### 请描述遇到的问题，以及您所期望的正确的结果

Tools • Dart 3.8.1 • DevTools 2.45.1，flutter_boost 4.6.5, 当设置warmUpEngine为true时，push flutter页面卡在FBFlutterViewContainer初始化，取消预热引擎能正常push，但是跳转时白屏时间较长

### 请说明如何操作会遇到上述问题

_No response_

### 在下面填入关键复现代码

```
```

### 复现的平台

iOS

### Flutter SDK版本

Tools • Dart 3.8.1 • DevTools 2.45.1

### FlutterBoost版本

4.6.5

### 是否延迟初始化FlutterBoost

No

### 解决方案

Start by reproducing the iOS navigation case with FlutterBoost 4.6.5, Dart 3.8.1, and warmUpEngine set to true. Inspect the FBFlutterViewContainer initialization path and compare it with navigation when engine warming is disabled. Done means pushing the Flutter page completes without hanging, while the disabled-warmup path does not regress with an excessive white screen.

Written by the indexing model from the issue text.