feat(admin): analytics dashboard

Sprint 27.

New features/admin/analytics/ module + net-new /:lang/backoffice/analytics
route + Dashboard Quick Action.

- revenue/orders/avg-order-value/sales-over-time/top-products computed by
  composing AdminOrdersLocalGateway (Sprint 23's seeded mock orders) - real
  aggregation over mock data, not a separate fabricated dataset
- products/categories counts from AdminProductsLocalGateway/
  AdminCategoriesLocalGateway
- visitors/funnels/heatmaps render pending-backend badges (no analytics
  pipeline exists anywhere in this system) rather than fabricated numbers,
  same convention as the Sprint 19 dashboard's pre-Sprint-23 Orders/Revenue
  cards
- plain div-bar chart (no charting library), 7/30/90-day range toggle,
  CSV export

docs/ADMIN.md + docs/BACKEND.md (new item 16) updated.

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

src/app/features/admin/analytics/pages/admin-analytics-page.component.scss

@@ -0,0 +1,13 @@
+.admin-analytics-page { display: grid; gap: 16px; padding: 16px; max-width: 1100px; margin: 0 auto; }
+.toolbar { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 10px; }
+.ranges { display: flex; gap: 6px; }
+.summary-grid { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 10px; }
+.summary-card { border: 1px solid var(--border-color, #d3dad9); border-radius: 12px; padding: 12px; display: grid; gap: 4px; background: #fff; }
+.summary-card span { font-size: 0.75rem; color: var(--text-secondary, #6b7280); }
+.summary-card strong { font-size: 1.1rem; }
+.card { display: grid; gap: 12px; padding: 16px; border: 1px solid var(--border-color, #d3dad9); border-radius: 16px; background: #fff; }
+.card h2 { margin: 0; font-size: 1.1rem; }
+.chart { display: flex; align-items: flex-end; gap: 3px; height: 140px; }
+.chart .bar { flex: 1; background: var(--color-primary, #2f8f5b); border-radius: 3px 3px 0 0; min-height: 2px; }
+.pending-section p { display: flex; align-items: center; gap: 8px; margin: 0; color: var(--text-secondary, #6b7280); }
+@media (max-width: 900px) { .summary-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }