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/features/admin/shell/admin-layout.component.html

@@ -44,8 +44,20 @@
     </ul>
 
     <ul class="admin-layout__nav-list admin-layout__nav-list--bottom">
-      @for (entry of navBottom; track $index) {
-        @if (entry.type === 'link' && entry.comingSoon) {
+      @for (entry of navBottom(); track $index) {
+        @if (entry.type === 'link' && entry.externalHref) {
+          <li>
+            <a
+              class="admin-layout__nav-link"
+              [href]="entry.externalHref"
+              [attr.target]="entry.externalHref.startsWith('mailto:') ? null : '_blank'"
+              [attr.rel]="entry.externalHref.startsWith('mailto:') ? null : 'noopener'"
+            >
+              <app-icon [name]="entry.icon" [size]="18" />
+              <span class="admin-layout__nav-label">{{ entry.labelKey | translate }}</span>
+            </a>
+          </li>
+        } @else if (entry.type === 'link' && entry.comingSoon) {
           <li>
             <button type="button" class="admin-layout__nav-link admin-layout__nav-link--disabled" disabled>
               <app-icon [name]="entry.icon" [size]="18" />
@@ -151,7 +163,7 @@
     </div>
   </header>
 
-  <main id="admin-content" class="admin-layout__content" tabindex="-1">
+  <main id="admin-content" class="admin-layout__content" [class.admin-density-compact]="density() === 'compact'" tabindex="-1">
     <router-outlet></router-outlet>
   </main>