feat: close stub-page gaps - profile login/logout, admin Reports/Settings, Help/Docs links

Sprint A: storefront header profile control (login/logout only, no menu),
wired to existing customer Telegram auth (AuthService).

Sprint B: backoffice/reports page, reuses AdminAnalyticsFacade (Sales,
Top Products, Marketplace Health cards + CSV export).

Sprint C: backoffice/settings page, admin UI density preference
(comfortable/compact), localStorage-persisted, applied to app-table
across all admin list pages.

Sprint D: admin bottom-nav Help -> mailto using existing supportEmail,
Documentation -> external link via new TenantConfig.documentationUrl.
AdminNavLink gains externalHref for non-routerLink nav entries.

Docs: docs/GLOBAL-SPRINT-PLAN.md tracks the full sprint breakdown.
docs/COMING-SOON-AUDIT.md removed, folded into docs/KNOWN-ISSUES.md.
docs/BACKEND.md updated with the new documentationUrl bootstrap field.

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

src/app/i18n/en.ts

@@ -12,6 +12,8 @@ export const en: Translations = {
     compare: 'Compare',
     openMenu: 'Open menu',
     closeMenu: 'Close menu',
+    login: 'Log in',
+    logout: 'Log out',
   },
   footer: {
     description: 'A modern marketplace for comfortable shopping',
@@ -1909,6 +1911,16 @@ export const en: Translations = {
     lastPublished: 'Last published',
     syncStatus: 'Sync',
   },
+  adminReports: {
+    sales: 'Sales',
+    topProducts: 'Top Products',
+    marketplaceHealth: 'Marketplace Health',
+  },
+  adminSettings: {
+    density: 'Table density',
+    densityExplain: 'Reduce row padding across backoffice list pages for a more compact view.',
+    densityCompact: 'Compact rows',
+  },
   adminAnalytics: {
     topProductsEmptyTitle: 'No product sales in this period',
     topProductsEmptyDescription: 'Try a wider date range.',
@@ -2060,6 +2072,8 @@ export const en: Translations = {
       monitoring: { title: 'Monitoring', description: 'Queue, webhook, and system event status' },
       analytics: { title: 'Analytics', description: 'Sales, products, and shopper behavior' },
       sellerManagement: { title: 'Seller Management', description: 'Onboard and manage independent sellers on your marketplace' },
+      reports: { title: 'Reports', description: 'Export sales, product, and marketplace health reports' },
+      settings: { title: 'Settings', description: 'Backoffice display preferences' },
     },
   },
   adminSellerManagement: {