chore: remove confirmed dead code

Dead code sweep verified manually against app.routes.ts, DI registries, and
cross-repo grep for every candidate (per prior false-positive incident with
knip on pages/**). Deleted only what has zero reachable reference:

Auth (unregistered, comment-only mention):
- core/auth/guards/ed25519-auth.guard.ts - ed25519AuthGuard never imported;
  only mentioned inside a doc-comment in admin-login-page.component.ts.
- core/auth/guards/permission.guard.ts - permissionGuard never imported.
- core/auth/interceptors/auth.interceptor.ts - authInterceptor not present
  in app.config.ts's withInterceptors([...]) list; not imported elsewhere.

Search feature:
- features/search/services/search-analytics.service.ts - SearchAnalyticsService
  never imported outside its own file.
- features/search/components/empty-results/* - app-search-empty-results
  selector never used in any template; search-bar.component.html implements
  its own inline @if (noResults) empty state instead.

Content management:
- features/content-management/pages/content-management-page.component.ts -
  thin wrapper around StaticPagesEditorComponent with zero route pointing at
  it in app.routes.ts. The rest of features/content-management/* (facade,
  static-pages-editor, page-editor, etc.) remains: it is used by
  project-editor and stays.

Backoffice CRUD scaffolding (re-verified the UI-COMPOSITION-REVIEW.md claim
independently): app.routes.ts backoffice section only loads
features/admin/{dashboard,products,categories,transactions,orders,customers,
moderation,users,monitoring,analytics} and features/backoffice/media. Grepped
every other backoffice/* folder for cross-references - none found.
- features/backoffice/{categories,customers,inventory,orders,products,settings}
  - each contained only a placeholder .gitkeep from the original scaffold
  commit (b957112); no real components were ever added, so this is not the
  "duplicate implementation" the prior doc described, just unused scaffold
  dirs. Removing corrects that doc's premise.
- features/backoffice/shared/backoffice-coming-soon-page.component.* - only
  consumer would have been those scaffold dirs; unreferenced elsewhere.
- assets/mock/backoffice/{customers,orders}/list.json - mock data with no
  corresponding fetch call; BackofficeDataProvider only exposes
  loadProducts()/loadCategories(), backed by the products/categories mock
  files, which are kept.

Dead shared barrels/models (no importer anywhere in src/app):
- shared/index.ts, shared/models/index.ts, shared/types/index.ts - unused
  re-export barrels.
- shared/models/domain/index.ts + user-preferences.model.ts (whole domain/
  subfolder) - UserPreferences interface has zero consumers.

Storefront pages (pages/public/platform-home.component.ts) - PlatformHomeComponent
has no route in app.routes.ts and is not imported anywhere; distinct from the
pages/category, pages/search, pages/info/**, pages/legal/**, pages/item-detail
components which ARE routed and were correctly left untouched.

Verification: npx tsc --noEmit -p tsconfig.app.json clean after each batch;
npm run build succeeded (pre-existing initial-bundle-budget warning only,
unrelated to this change).

src/app/pages/public/platform-home.component.ts

@@ -1,49 +0,0 @@
-import { ChangeDetectionStrategy, Component, inject, signal } from '@angular/core';
-import { Router } from '@angular/router';
-import { DynamicPageLayoutComponent } from '../../layouts/containers/dynamic-page-layout.component';
-import { PageRenderModel } from '../../dynamic-renderer/page-renderer/page-renderer.model';
-import { WebsiteRuntimeFacade } from '../../facades/website/website-runtime.facade';
-import { TranslatePipe } from '../../i18n/translate.pipe';
-
-@Component({
-  selector: 'app-platform-home',
-  standalone: true,
-  imports: [DynamicPageLayoutComponent, TranslatePipe],
-  template: `
-    @if (loading()) {
-      <section class="platform-loading section">
-        <div class="page-container">{{ 'platform.loadingPage' | translate }}</div>
-      </section>
-    } @else if (model()) {
-      <app-dynamic-page-layout [model]="model()" />
-    } @else {
-      <section class="platform-empty section">
-        <div class="page-container">{{ 'platform.emptyConfig' | translate }}</div>
-      </section>
-    }
-  `,
-  styles: [
-    `
-      .platform-loading, .platform-empty { padding: 2rem; color: var(--text-secondary, #667a77); }
-    `
-  ],
-  changeDetection: ChangeDetectionStrategy.OnPush
-})
-export class PlatformHomeComponent {
-  readonly model = signal<PageRenderModel | null>(null);
-  readonly loading = signal(true);
-  private readonly router = inject(Router);
-
-  constructor(private readonly websiteRuntime: WebsiteRuntimeFacade) {
-    this.websiteRuntime.getPageRenderModelForUrl(this.router.url).subscribe({
-      next: (model) => {
-        this.model.set(model);
-        this.loading.set(false);
-      },
-      error: () => {
-        this.model.set(null);
-        this.loading.set(false);
-      }
-    });
-  }
-}