feat(admin): sprint 19 admin dashboard, routing, i18n

- Add admin dashboard feature (models/gateway/facade/components/page)
- Wire admin/products routes and backoffice coming-soon placeholders
- Add lastPublishedAt to ProjectEditorFacade/state
- Add dashboard i18n keys (en/ru/hy) and docs/ADMIN.md

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/features/admin/dashboard/components/admin-dashboard-activity.component.ts

@@ -0,0 +1,21 @@
+import { ChangeDetectionStrategy, Component, Input } from '@angular/core';
+import { CommonModule } from '@angular/common';
+import { TranslatePipe } from '../../../../i18n/translate.pipe';
+
+export interface AdminDashboardActivityViewEntry {
+  id: string;
+  labelKey: string;
+  timeText: string;
+}
+
+@Component({
+  selector: 'app-admin-dashboard-activity',
+  standalone: true,
+  imports: [CommonModule, TranslatePipe],
+  templateUrl: './admin-dashboard-activity.component.html',
+  styleUrls: ['./admin-dashboard-activity.component.scss'],
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+export class AdminDashboardActivityComponent {
+  @Input() entries: AdminDashboardActivityViewEntry[] = [];
+}