feat: initial theming

src/app/app.config.ts

@@ -8,6 +8,7 @@ import {
   provideBrowserGlobalErrorListeners,
 } from "@angular/core";
 import { provideRouter } from "@angular/router";
+// eslint-disable-next-line import/extensions -- This is not a file extension.
 import { routes } from "./app.routes";
 
 export const appConfig: ApplicationConfig = {