fix(admin): Seller Management UX review - a11y label fix, icon list, review doc

Reviewed the Phase 1 UI against every other Backoffice page. Found and
fixed 2 real issues; everything else verified already consistent
(built entirely from shared components, so hover/focus/dialog-a11y/
dark-readiness/contrast come from those components, not reinvented).

Fixed:
- Message textarea had no id/aria-describedby wiring (app-input
  self-wires this via injected FormFieldContext; the raw textarea -
  no dedicated textarea component exists yet - never got it, so the
  visible label's `for` pointed nowhere). Added explicit aria-label
  bound to the same translation key as the visible label.
- Learn More dialog's feature list would render native browser
  bullets (no global list-style reset exists outside details>summary
  in styles.scss). Replaced with checkCircle icon + text rows,
  consistent with how the rest of the app pairs icons with list/status
  meaning.

Added docs/architecture/foundation/Seller-Management-UX-Review.md
documenting both fixes plus everything checked and confirmed already
consistent (empty-state usage, icon reuse, translations completeness
across en/ru/hy, responsive at 1280px/375px, dialog a11y verified via
accessibility tree not assumed).

tsc --noEmit clean, arch:check (boundaries + cycles) clean. Live-
verified: Learn More dialog shows all 6 items each with an icon
(confirmed via DOM query), textarea aria-label confirmed
"Сообщение", no console errors.

src/app/features/admin/seller-management/pages/admin-seller-management-page.component.html

@@ -53,6 +53,7 @@
         class="admin-seller-management-page__textarea"
         rows="4"
         [placeholder]="'adminSellerManagement.requestDialog.messagePlaceholder' | translate"
+        [attr.aria-label]="'adminSellerManagement.requestDialog.messageLabel' | translate"
         [ngModel]="form().message"
         (ngModelChange)="updateMessage($event)"
         name="message"
@@ -92,12 +93,12 @@
 >
   <app-badge variant="info">{{ 'adminSellerManagement.learnMoreDialog.comingSoonBadge' | translate }}</app-badge>
   <ul class="admin-seller-management-page__feature-list">
-    <li>{{ 'adminSellerManagement.learnMoreDialog.features.sellerDashboards' | translate }}</li>
-    <li>{{ 'adminSellerManagement.learnMoreDialog.features.sellerStorefronts' | translate }}</li>
-    <li>{{ 'adminSellerManagement.learnMoreDialog.features.sellerPermissions' | translate }}</li>
-    <li>{{ 'adminSellerManagement.learnMoreDialog.features.sellerAnalytics' | translate }}</li>
-    <li>{{ 'adminSellerManagement.learnMoreDialog.features.productOwnership' | translate }}</li>
-    <li>{{ 'adminSellerManagement.learnMoreDialog.features.marketplaceAdministration' | translate }}</li>
+    @for (featureKey of learnMoreFeatureKeys; track featureKey) {
+      <li class="admin-seller-management-page__feature-item">
+        <app-icon name="checkCircle" [size]="18" />
+        <span>{{ ('adminSellerManagement.learnMoreDialog.features.' + featureKey) | translate }}</span>
+      </li>
+    }
   </ul>
   <div class="admin-seller-management-page__dialog-actions">
     <app-button variant="primary" (click)="closeLearnMoreDialog()">

src/app/features/admin/seller-management/pages/admin-seller-management-page.component.scss

@@ -70,11 +70,23 @@
 .admin-seller-management-page__feature-list {
   display: flex;
   flex-direction: column;
-  gap: var(--space-xs, 0.375rem);
+  gap: var(--space-sm, 0.5rem);
   margin: var(--space-md, 1rem) 0 0;
-  padding-inline-start: var(--space-md, 1rem);
+  padding: 0;
+  list-style: none;
+}
+
+.admin-seller-management-page__feature-item {
+  display: flex;
+  align-items: center;
+  gap: var(--space-sm, 0.5rem);
   color: var(--text-primary, #1f322d);
   font-size: var(--font-size-md, 0.9375rem);
+
+  app-icon {
+    flex-shrink: 0;
+    color: var(--success-color, #2e7d32);
+  }
 }
 
 @media (prefers-reduced-motion: reduce) {

src/app/features/admin/seller-management/pages/admin-seller-management-page.component.ts

@@ -59,6 +59,15 @@ export class AdminSellerManagementPageComponent {
 
   protected readonly form = signal<SellerAccessRequest>({ company: '', email: '', message: '' });
 
+  protected readonly learnMoreFeatureKeys = [
+    'sellerDashboards',
+    'sellerStorefronts',
+    'sellerPermissions',
+    'sellerAnalytics',
+    'productOwnership',
+    'marketplaceAdministration'
+  ] as const;
+
   protected openRequestDialog(): void {
     this.form.set({ company: '', email: '', message: '' });
     this.requestDialogOpen.set(true);