Rework of Web-Projects

[dbeuchler]

The web projects were migrated from one angular version to another. New conventions were not applied.

Here are some conventions we should apply:

• All components, directives, and pipes are standalone. Only use standalone: false for legacy compatibility.
• Prefer signals over RxJS for component state management.
• Use @if, @for, @switch, @defer instead of structural directives.
• Write code that works without zone.js (Angular 21 default).
• Prefer inject() over Constructor Injection
• Check usage of deprecated provideAnimations
• Replace ngOnInit by appropriate signal handling
• Sometimes there are extensions for promises to convert them to observables. I already refactored some usages to lastValueFrom to get rid of the extensions. It is still mixed and should be refactored. ng-openapi-gen supports generation of observables. Maybe this is a good point to start and harmonize.