feat(challenge24): create test harness

apps/create-harness/src/app/app.component.ts

@@ -0,0 +1,26 @@
+import { Component, signal } from '@angular/core';
+import { SliderComponent } from './slider.component';
+
+@Component({
+  standalone: true,
+  imports: [SliderComponent],
+  selector: 'app-root',
+  template: `
+    <h2>Slider 1: {{ slider1Value() }}</h2>
+    <app-slider
+      [step]="3"
+      [minValue]="10"
+      [maxValue]="30"
+      (valueChange)="slider1Value.set($event)" />
+    <h2>Slider 2: {{ slider2Value() }}</h2>
+    <app-slider
+      [step]="10"
+      [maxValue]="1000"
+      (valueChange)="slider2Value.set($event)" />
+  `,
+  styles: [''],
+})
+export class AppComponent {
+  slider1Value = signal(0);
+  slider2Value = signal(0);
+}