fix: replace deprecated *ngIf with @if control flow in OTP component

- Migrated all *ngIf directives to modern @if syntax in otp.component.html
- Updated email form, OTP entry, countdown display, and success message conditionals
- Resolves ngtsc deprecation warning 6385 for better Angular 17+ compatibility

src/app/app.config.ts

@@ -3,11 +3,15 @@ import { provideRouter } from '@angular/router';
 
 import { routes } from './app.routes';
 import { provideClientHydration, withEventReplay } from '@angular/platform-browser';
+import { provideHttpClient, withFetch, withInterceptorsFromDi } from '@angular/common/http';
+import { httpInterceptorProviders } from './interceptors';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideBrowserGlobalErrorListeners(),
     provideZonelessChangeDetection(),
+    provideHttpClient(withInterceptorsFromDi(), withFetch()),
+    httpInterceptorProviders,
     provideRouter(routes), provideClientHydration(withEventReplay())
   ]
 };