Convert components to standalone and implement route-based loading

Refactored Angular components to standalone modules, enhancing modularity and reducing dependency on `AppModule`. Updated routes to facilitate lazy loading for improved performance and maintainability. Replaced `platformBrowserDynamic` with `bootstrapApplication` for modern bootstrapping.

frontend/src/app/about/about.component.ts

@@ -1,9 +1,15 @@
 import {Component} from '@angular/core';
 import {ScrollService} from '../scroll/scroll.service';
+import {CommonModule} from '@angular/common';
+import {HeaderComponent} from '../header/header.component';
 
 @Component({
   selector: 'app-about',
-  standalone: false,
+  standalone: true,
+  imports: [
+    CommonModule,
+    HeaderComponent
+  ],
   templateUrl: './about.component.html',
   styleUrl: './about.component.scss'
 })