add initial Angular components, services, and routing setup

client/src/app/pages/not-found/not-found.component.ts

@@ -0,0 +1,12 @@
+import { Component } from '@angular/core';
+
+@Component({
+  selector: 'app-not-found',
+  standalone: true,
+  imports: [],
+  templateUrl: './not-found.component.html',
+  styleUrl: './not-found.component.css'
+})
+export class NotFoundComponent {
+
+}