ServiceWorker registration fails in Facebook/Instagram in-app browser on iOS

When using the Firebase Messaging service with Angular 19.1.4 in the Facebook/Instagram in-app browser on iOS devices, the following error occurs:
```typescript
TypeError: undefined is not an object (evaluating 'navigator.serviceWorker.addEventListener')
```

### Environment
- **Platform**: iOS
- **Browser**: Facebook/Instagram in-app browser
- **Framework**: Angular 19.1.4
- **Dependencies**:
- @angular/core: 19.1.4
- @angular/common: 19.1.4
- @angular/platform-browser: 19.1.4
- **Service**: Firebase Cloud Messaging

### Technical Details
The error occurs during the messaging service initialization when attempting to add an event listener to the ServiceWorker. The specific line causing the issue is:
```typescript
navigator.serviceWorker.addEventListener('message', e => messageEventListener(messaging as MessagingService, e));
```

### Root Cause
The Facebook/Instagram in-app browser on iOS does not support or properly expose the ServiceWorker API, causing `navigator.serviceWorker` to be undefined. This issue persists even with the latest Angular 19 framework.

### Impact
- Firebase Cloud Messaging service initialization fails
- Push notifications cannot be registered or received
- Affects only users accessing the Angular 19 application through Facebook/Instagram in-app browser on iOS devices

从 issue 中显示的 messaging-service 初始化调用开始，并在 Facebook/Instagram 的 iOS 应用内浏览器中重现它。跟踪 navigator.serviceWorker 的访问方式；当 API 不可用时初始化不再抛出错误，并且已在支持的环境中验证 push 行为，即表示完成。

由索引模型根据 Issue 内容生成。