feat: challenge 45 React in Angular

Add new challenge: React in Angular.

apps/angular/react-in-angular/src/app/react/post.component.ts

@@ -0,0 +1,17 @@
+import { Component, EventEmitter, input, Output } from '@angular/core';
+
+type Post = { title: string; description: string; pictureLink: string };
+
+@Component({
+  standalone: true,
+  selector: 'app-post',
+  template: `
+    <div></div>
+  `,
+  styles: [''],
+})
+export class PostComponent {
+  post = input<Post | undefined>(undefined);
+  isSelected = input<boolean>(false);
+  @Output() selectPost = new EventEmitter<void>();
+}