add api services to frontend

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

@@ -1,8 +1,15 @@
 import { Component, OnInit } from '@angular/core';
+import { Router } from '@angular/router';
 
 @Component({
   selector: 'app-header',
   templateUrl: './header.component.html',
   styleUrls: ['./header.component.scss'],
 })
-export class HeaderComponent {}
+export class HeaderComponent {
+  constructor(private router: Router) {}
+
+  doLogin() {
+    this.router.navigate(['/login']);
+  }
+}