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>

docs/NEXT_PHASE.md

@@ -20,4 +20,4 @@ Wire real error tracking/APM and a real event source for the admin Monitoring pa
 
 ## Phase 5 — Version 2 ideas
 
-Everything in `docs/PRODUCT_BACKLOG.md` (dark mode, brand-color contrast decision, advanced analytics, additional payment providers, Contacts page content) and `docs/FUTURE_FEATURES.md` (Angular 22 upgrade, cart-modal composition cleanup) — none of it scheduled, all of it deliberately deferred past initial launch.
+Everything in `docs/PRODUCT_BACKLOG.md` (dark mode, brand-color contrast decision, advanced analytics, additional payment providers, Contacts page content) and `docs/FUTURE_FEATURES.md` (Angular 22 upgrade, cart-modal composition cleanup) — none of it scheduled, all of it deliberately deferred past initial launch. The former stub-page/dead-toggle inventory (profile menu, admin Reports, admin Settings, Documentation/Help) is closed — see `docs/GLOBAL-SPRINT-PLAN.md` and `docs/KNOWN-ISSUES.md` "Fixed (this cycle)".