feat(diagnostics): add health engine

src/app/app.routes.ts

@@ -1,5 +1,6 @@
 import { Routes } from '@angular/router';
 import { languageGuard } from './guards/language.guard';
+import { environment } from '../environments/environment';
 
 // Core routes (same across all brands)
 const coreRoutes: Routes = [
@@ -67,6 +68,10 @@ const cmsContentRoutes: Routes = [];
 
 // All routes sit under a :lang prefix (e.g. /ru/cart, /en/product/5)
 export const routes: Routes = [
+  ...(environment.production ? [] : [{
+    path: '__diagnostics',
+    loadComponent: () => import('./features/diagnostics/components/diagnostics-page.component').then(m => m.DiagnosticsPageComponent)
+  }]),
   {
     path: ':lang',
     canActivate: [languageGuard],