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

從 issue 中顯示的 messaging-service 初始化呼叫開始，並在 Facebook/Instagram 的 iOS 應用程式內瀏覽器中重現它。追蹤 navigator.serviceWorker 的存取方式；當 API 無法使用時初始化不再擲出錯誤，且已在支援的環境中驗證 push 行為，即表示完成。

由索引模型根據 Issue 內容生成。