Remove SSR support and associated server-side code.

This change eliminates Angular server-side rendering (SSR) features, including related files, dependencies, and configurations, simplifying the codebase. The update also adjusts routing and references to support client-side rendering exclusively.

frontend/src/app/app.config.ts

@@ -2,8 +2,7 @@ import { ApplicationConfig, provideZoneChangeDetection } from '@angular/core';
 import { provideRouter } from '@angular/router';
 
 import { routes } from './app.routes';
-import { provideClientHydration, withEventReplay } from '@angular/platform-browser';
 
 export const appConfig: ApplicationConfig = {
-  providers: [provideZoneChangeDetection({ eventCoalescing: true }), provideRouter(routes), provideClientHydration(withEventReplay())]
+  providers: [provideZoneChangeDetection({ eventCoalescing: true }), provideRouter(routes)]
 };