Add IMDb movie importer feature and unify header

Introduces a new movie importer feature allowing admins to search and import movies from IMDb, including new components for search, result display, and error handling. Replaces the schedule header with a reusable menu header component. Updates routing, navigation, and HTTP service to support the new importer. Adds a poster placeholder image and improves poster error handling.

src/app/menu-header/menu-header.component.ts

@@ -0,0 +1,15 @@
+import { Component, input, output } from '@angular/core';
+
+@Component({
+  selector: 'app-menu-header',
+  standalone: false,
+  templateUrl: './menu-header.component.html',
+  styleUrl: './menu-header.component.css'
+})
+export class MenuHeaderComponent {
+  title = input.required<string>();
+  icon = input<string>();
+
+  searchBar = input<boolean>(false);
+  movieSearchResult = output<string>();
+}