refactor: Update TodoSkeletonComponent to use @for control flow

I've updated the `TodoSkeletonComponent` template to use the modern Angular built-in `@for` control flow, replacing the previous `*ngFor` directive.

This change aligns the component with current Angular best practices for template syntax. The visual structure and functionality of the skeleton items remain the same as per the previous refinement.

Author: google-labs-jules[bot]

projects/showcase/src/app/ui/todo-skeleton/todo-skeleton.component.ts

@@ -10,11 +10,11 @@ import { MatCardModule } from '@angular/material/card';
   selector: 'showcase-todo-skeleton',
   imports: [CommonModule, MatCardModule],
   template: `
-    <div *ngFor="let _ of [].constructor(repeat())">
+    @for (_ of [].constructor(repeat()); track $index) {
       <mat-card class="mb-4 p-4">
         <div class="animate-pulse flex items-center justify-between w-full">
           <!-- Left part: Placeholder for checkbox/icon and description -->
-          <div class="flex items-center gap-3 w-full"> <!-- Increased gap slightly for skeleton if needed, original is gap-6 -->
+          <div class="flex items-center gap-3 w-full">
             <!-- Checkbox placeholder -->
             <div class="h-6 w-6 bg-gray-300 rounded"></div>
             <!-- Description placeholder -->
@@ -27,7 +27,7 @@ import { MatCardModule } from '@angular/material/card';
           </div>
         </div>
       </mat-card>
-    </div>
+    }
   `,
   styles: `
     :host {