refactor: migrate tenant bootstrap to use SSR state caching and update button components to use CSS tenant variables

src/app/app.config.ts

@@ -1,4 +1,4 @@
-import { provideHttpClient } from '@angular/common/http';
+import { provideHttpClient, withFetch } from '@angular/common/http';
 import { ApplicationConfig, provideAppInitializer, provideBrowserGlobalErrorListeners } from '@angular/core';
 import { provideRouter } from '@angular/router';
 import { provideClientHydration } from '@angular/platform-browser';
@@ -11,7 +11,7 @@ export const appConfig: ApplicationConfig = {
     provideBrowserGlobalErrorListeners(),
     provideRouter(routes),
     provideClientHydration(),
-    provideHttpClient(),
+    provideHttpClient(withFetch()),
     provideAppInitializer(tenantBootstrap)
   ]
 };