Add Expert Angular Frontend Engineer custom Agent

[0x1bitcrack3r]

Pull Request Checklist

• I have read and followed the [CONTRIBUTING.md](https://github.com/github/awesome-copilot/blob/main/CONTRIBUTING.md) guidelines.
• My contribution adds a new instruction, prompt, or chat mode file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, or chat mode with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.

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Description

This PR adds a comprehensive Angular 19 Expert Frontend Engineer chat mode designed for developers building production-ready applications using Angular's modern architecture, signals-based reactivity, and cutting-edge Angular platform features.

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Type of Contribution

• New chat mode file.

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Additional Notes

Key Features:

• Signals Architecture with signal(), computed(), effect(), linkedSignal() (Angular 19), and full toSignal() / toObservable() RxJS interop
• Signal-Based Component APIs replacing @Input() / @Output() / @ViewChild with input(), output(), model(), viewChild(), and contentChild()
• New Control Flow Syntax using @if, @for (with required track), @switch, and @defer with @placeholder, @loading, and @error blocks — replacing legacy structural directives entirely
• @let Template Variables (Angular 19) for clean in-template declarations without component class boilerplate
• linkedSignal() (Angular 19) for signals that derive from a source but can also be independently overridden
• SSR & Incremental Hydration with route-level render modes (Prerender, Server, Client) and @defer (hydrate on viewport / interaction) (Angular 19)
• Standalone Components by Default with no NgModules, bootstrapApplication, and environment providers
• Zoneless Change Detection via provideZonelessChangeDetection() for maximum performance
• Functional Router Patterns including functional guards, resolvers, withComponentInputBinding(), and lazy-loaded routes
• Typed Reactive Forms with FormControl<T>, FormGroup<Schema>, custom validators, and async validation
• Functional HTTP Interceptors using HttpInterceptorFn with provideHttpClient(withFetch())
• RxJS Interop with takeUntilDestroyed(), toSignal(), and toObservable() for seamless Observable-to-signal bridging
• Signal-Based State Services using signal(), computed(), and .asReadonly() as a lightweight NgRx alternative
• SSR-Safe Browser Guards with isPlatformBrowser(), afterNextRender(), and afterRender()
• NgOptimizedImage for automatic LCP image optimization, lazy loading, and width/height enforcement
• Angular Material 3 with design tokens, theming, and CDK utilities
• Accessibility with Angular CDK a11y, live announcer, focus trap, ARIA patterns, and WCAG 2.1 AA compliance
• Testing with Angular Testing Library, Spectator, component harnesses, and Playwright e2e

This chat mode is particularly useful for teams building modern Angular 19 applications that demand performance, scalability, type safety, and design system consistency while adhering to the latest signals-based reactive architecture and standalone component model.

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By submitting this pull request, I confirm that my contribution abides by the [Code of Conduct](../CODE_OF_CONDUCT.md) and will be licensed under the MIT License.

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