feat: add EnvBanner component for non-production environments

Standalone component that renders a small banner whenever
environment.production is false, so the local dev build is never
mistaken for the real app.

myteamwallet_frontend_modern/src/app/shared/env-banner/env-banner.ts

@@ -0,0 +1,13 @@
+import { Component } from '@angular/core';
+import { environment } from '../../../environments/environment';
+
+export const ENV_BANNER_HEIGHT_PX = 28;
+
+@Component({
+  selector: 'app-env-banner',
+  templateUrl: './env-banner.html',
+  styleUrl: './env-banner.scss',
+})
+export class EnvBanner {
+  protected readonly showBanner = !environment.production;
+}