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/movie-import-no-search-result/movie-import-no-search-result.component.html

@@ -0,0 +1,5 @@
+<div class="flex flex-col items-center justify-center py-12 text-gray-500 h-100 m-auto">
+  <mat-icon class="text-6xl mb-4 opacity-50" style="font-size: 50px; width: 50px; height: 50px;">search_off</mat-icon>
+  <p class="text-lg">Kein Film gefunden</p>
+  <p class="text-sm">Für '{{ search() }}' konnten über IMDb keine Filme gefunden werden.</p>
+</div>

src/app/movie-import-no-search-result/movie-import-no-search-result.component.ts

@@ -0,0 +1,11 @@
+import { Component, input } from '@angular/core';
+
+@Component({
+  selector: 'app-movie-import-no-search-result',
+  standalone: false,
+  templateUrl: './movie-import-no-search-result.component.html',
+  styleUrl: './movie-import-no-search-result.component.css'
+})
+export class MovieImportNoSearchResultComponent {
+ search = input.required<string>();
+}