Extract search bar into a standalone component and fix header design.

frontend/src/app/components/publications-search-bar/publications-search-bar.service.ts

@@ -0,0 +1,18 @@
+import { HttpParams } from "@angular/common/http";
+import { inject, Injectable } from "@angular/core";
+import { Router } from "@angular/router";
+import { BehaviorSubject } from "rxjs";
+
+@Injectable()
+export class PublicationsSearchBarService {
+    private router = inject(Router);
+    private criteriaSubject = new BehaviorSubject<string>('');
+
+    private cri
+
+    searchPublications(): void {
+        let queryParams = new HttpParams();
+        queryParams = queryParams.set('query', this.criteriaSubject.value);
+        this.router.navigate(['/publications'], {queryParams});
+    }
+}