Add disconnection and minor improvements on login page.

frontend/src/app/components/header/header.component.ts

@@ -1,13 +1,21 @@
-import { Component } from '@angular/core';
+import { Component, inject } from '@angular/core';
 import { MatIconModule } from '@angular/material/icon';
 import { MatButtonModule } from '@angular/material/button';
 import { RouterModule } from '@angular/router';
+import { AuthenticationService } from '../../core/service/authentication.service';
+import { CommonModule } from '@angular/common';
 
 @Component({
   selector: 'app-header',
   standalone: true,
-  imports: [MatButtonModule, MatIconModule, RouterModule],
+  imports: [CommonModule, MatButtonModule, MatIconModule, RouterModule],
   templateUrl: './header.component.html',
   styleUrl: './header.component.scss',
 })
-export class HeaderComponent {}
+export class HeaderComponent {
+  private authenticationService = inject(AuthenticationService);
+
+  get isAuthenticated(): boolean {
+    return this.authenticationService.isAuthenticated();
+  }
+}