feat(admin): implement analytics and monitoring center

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

- Business Dashboard: revenue/orders/customers/AOV/top products/low stock/recent activity/warnings/completion% (Overview tab)
- Marketplace Health: real completion checks (images, SEO, categories, reviews, orders, translations, homepage, backend, performance) with clickable recommendations
- Product Analytics: top selling/most reviewed/worst rated/hidden/archived counts; top-viewed honestly marked Unknown (no view tracking exists)
- Customer Analytics: new/returning customers, average spend, retention - derived from real order data
- Search & Traffic tabs: honest 'Unknown - available after backend integration' placeholders, no fabricated numbers
- Recommendations engine: actionable cards (missing images/SEO/category, empty categories, incomplete homepage, unpublished static pages) linking to the relevant admin page
- System Monitoring: added real draft/publish/sync/backend-connectivity state from AdminDashboardFacade
- CSV export extended to top products and health checks; added print action
- New adminAnalytics.* and adminMarketplaceHealth.* i18n namespaces (en/ru/hy), no raw i18n keys
- Reused existing shared UI (app-table/app-badge/app-skeleton/app-empty-state) and content-health-widget completion-meter pattern - no new backend APIs, no storage changes

src/app/i18n/translations.ts

@@ -1601,10 +1601,100 @@ export interface Translations {
   adminMonitoring: {
     eventsEmptyTitle: string;
     eventsEmptyDescription: string;
+    systemState: string;
+    backendConnectivity: string;
+    connected: string;
+    loading: string;
+    draftState: string;
+    unsavedChanges: string;
+    noDraft: string;
+    lastSaved: string;
+    lastPublished: string;
+    syncStatus: string;
   };
   adminAnalytics: {
     topProductsEmptyTitle: string;
     topProductsEmptyDescription: string;
+    print: string;
+    tabsLabel: string;
+    tab: {
+      overview: string;
+      health: string;
+      products: string;
+      customers: string;
+      search: string;
+      traffic: string;
+      recommendations: string;
+    };
+    revenue: string;
+    orders: string;
+    customers: string;
+    avgOrderValue: string;
+    conversion: string;
+    completionPercent: string;
+    unknown: string;
+    salesChart: string;
+    quantitySold: string;
+    lowStock: string;
+    lowStockEmptyTitle: string;
+    quantity: string;
+    status: string;
+    recentActivity: string;
+    recentActivityEmptyTitle: string;
+    activityDraftSaved: string;
+    activityPublished: string;
+    warnings: string;
+    topViewed: string;
+    hiddenProducts: string;
+    archivedProducts: string;
+    mostReviewed: string;
+    worstRated: string;
+    noReviewedProducts: string;
+    reviewCount: string;
+    avgRating: string;
+    newCustomers: string;
+    returningCustomers: string;
+    averageSpend: string;
+    retention: string;
+    searchAnalytics: string;
+    trafficAnalytics: string;
+    availableAfterBackend: string;
+    pendingBackend: string;
+    pendingBackendHint: string;
+    funnelsHeatmaps: string;
+    visitors: string;
+    products: string;
+    categories: string;
+  };
+  adminMarketplaceHealth: {
+    title: string;
+    complete: string;
+    recommendationsTitle: string;
+    recommendNone: string;
+    checkImages: string;
+    checkSeo: string;
+    checkCategories: string;
+    checkReviews: string;
+    checkOrders: string;
+    checkTranslations: string;
+    checkHomepage: string;
+    checkBackend: string;
+    checkPerformance: string;
+    recommendImages: string;
+    recommendImagesCount: string;
+    recommendSeo: string;
+    recommendSeoCount: string;
+    recommendCategory: string;
+    recommendCategoryCount: string;
+    recommendEmptyCategories: string;
+    recommendEmptyCategoriesCount: string;
+    recommendHomepage: string;
+    recommendStaticPages: string;
+    severity: {
+      info: string;
+      warning: string;
+      critical: string;
+    };
   };
   adminShell: {
     skipToContent: string;