bug: Error adding PWA to Ionic 8 in Angular 18

### Prerequisites

- [X] I have read the [Contributing Guidelines](https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#creating-an-issue).
- [X] I agree to follow the [Code of Conduct](https://ionicframework.com/code-of-conduct).
- [X] I have searched for [existing issues](https://github.com/ionic-team/ionic-framework/issues) that already report this problem, without success.

### Ionic Framework Version

v8.x

### Current Behavior

With a new Ionic 8 project with Angular 18, I follow the instructions about adding a PWA as stated in:

https://ionicframework.com/docs/angular/pwa

Everything is created ok, but the manifest.webmanifest and the icons are created in a folder called "public".

Once deployed to Firebase, there is the following error:

Manifest: Line: 1, column: 1, Syntax error.

And in the developer tools sources, we can see the manifest.webmanifest but the contents are the same as index.html.

### Expected Behavior

The expectesd behaviour is the correct ceration or integration of manifest.webmanifest when adding PWA, as it happens when we create an Angular 18 project and add the PWA following the same steps as before.

It used to work ok with ionic 7 and Angular 17.

### Steps to Reproduce

1. ionic start test tabs
2. ng add @angular/pwa
3. follow the steps of https://ionicframework.com/docs/angular/pwa

### Code Reproduction URL

https://github.com/jrbistuer/pwa-error

### Ionic Info

Ionic:

Ionic CLI : 7.2.0 (/Users/jrbistuer/.nvm/versions/node/v20.12.2/lib/node_modules/@ionic/cli)
Ionic Framework : @ionic/angular 8.2.6
@angular-devkit/build-angular : 18.1.2
@angular-devkit/schematics : 18.1.2
@angular/cli : 18.1.2
@ionic/angular-toolkit : 11.0.1

Capacitor:

Capacitor CLI : 6.1.1
@capacitor/android : not installed
@capacitor/core : 6.1.1
@capacitor/ios : not installed

Utility:

cordova-res : 0.15.4
native-run : 2.0.1

System:

NodeJS : v20.12.2 (/Users/jrbistuer/.nvm/versions/node/v20.12.2/bin/node)
npm : 10.5.0
OS : macOS Unknown

### Additional Information

_No response_