feat(media): add Media Manager UI (grid, upload, delete)

MediaLibraryPageComponent replaces the coming-soon placeholder at
/backoffice/media. Built entirely on Sprint 6 Design System primitives
(app-card, app-button, app-input, app-empty-state, app-dialog, app-pagination,
app-skeleton) and Sprint 4 Task 2's MediaRepository/MockMediaRepository.

- Grid view with per-tile filename/size and delete action
- Hidden native file input triggered by an app-button, uploads via
  MediaLibraryFacade -> MediaRepository.upload()
- Delete requires confirmation through app-dialog (destructive action)
- Search + pagination wired to MockMediaRepository's list() params
- Loading state shows app-skeleton tiles; empty state shows app-empty-state
- New mediaLibrary.* translation namespace across en/ru/hy

Verified in browser (via a temporary unguarded route, reverted before
commit - /backoffice/media itself requires Telegram QR admin auth not
available in this session): empty state renders correctly with translated
copy, search input and upload button present, no console errors.

src/app/features/backoffice/media/facade/media-library.facade.ts

@@ -0,0 +1,71 @@
+import { Injectable, inject, signal } from '@angular/core';
+import { MediaRepository } from '../../../../core/media/media-repository';
+import { MediaAsset } from '../../../../core/media/models/media-asset.model';
+
+const PAGE_SIZE = 24;
+
+@Injectable({ providedIn: 'root' })
+export class MediaLibraryFacade {
+  private readonly repository = inject(MediaRepository);
+
+  readonly items = signal<MediaAsset[]>([]);
+  readonly total = signal(0);
+  readonly loading = signal(false);
+  readonly uploading = signal(false);
+  readonly error = signal<string | null>(null);
+  readonly search = signal('');
+  readonly page = signal(1);
+
+  async load(): Promise<void> {
+    this.loading.set(true);
+    this.error.set(null);
+    try {
+      const result = await this.repository.list({
+        page: this.page(),
+        pageSize: PAGE_SIZE,
+        search: this.search(),
+      });
+      this.items.set(result.items);
+      this.total.set(result.total);
+    } catch {
+      this.error.set('Failed to load media assets.');
+    } finally {
+      this.loading.set(false);
+    }
+  }
+
+  setSearch(value: string): void {
+    this.search.set(value);
+    this.page.set(1);
+    void this.load();
+  }
+
+  setPage(page: number): void {
+    this.page.set(page);
+    void this.load();
+  }
+
+  async upload(file: File): Promise<void> {
+    this.uploading.set(true);
+    this.error.set(null);
+    try {
+      await this.repository.upload(file);
+      this.page.set(1);
+      await this.load();
+    } catch {
+      this.error.set('Failed to upload file.');
+    } finally {
+      this.uploading.set(false);
+    }
+  }
+
+  async remove(id: string): Promise<void> {
+    this.error.set(null);
+    try {
+      await this.repository.remove(id);
+      await this.load();
+    } catch {
+      this.error.set('Failed to delete file.');
+    }
+  }
+}

src/app/features/backoffice/media/media-library-page.component.html

@@ -0,0 +1,73 @@
+<section class="media-page">
+  <div class="media-page__toolbar">
+    <h2>{{ 'mediaLibrary.title' | translate }}</h2>
+    <div class="media-page__toolbar-actions">
+      <app-input
+        [ngModel]="facade.search()"
+        (ngModelChange)="facade.setSearch($event)"
+        [placeholder]="'mediaLibrary.searchPlaceholder' | translate"
+      />
+      <input
+        #fileInput
+        type="file"
+        accept="image/*,application/pdf"
+        hidden
+        (change)="onFileSelected($event)"
+      />
+      <app-button variant="primary" [loading]="facade.uploading()" (click)="triggerFileInput()">
+        {{ (facade.uploading() ? 'mediaLibrary.uploading' : 'mediaLibrary.upload') | translate }}
+      </app-button>
+    </div>
+  </div>
+
+  @if (facade.loading()) {
+    <div class="media-page__grid">
+      @for (i of [1, 2, 3, 4, 5, 6]; track i) {
+        <app-skeleton shape="rect" height="140px" />
+      }
+    </div>
+  } @else if (facade.items().length === 0) {
+    <app-empty-state
+      [title]="'mediaLibrary.emptyTitle' | translate"
+      [description]="'mediaLibrary.emptyDescription' | translate"
+    />
+  } @else {
+    <div class="media-page__grid">
+      @for (asset of facade.items(); track asset.id) {
+        <app-card padding="sm">
+          <div class="media-tile">
+            @if (asset.mimeType.startsWith('image/')) {
+              <img class="media-tile__preview" [src]="asset.url" [alt]="asset.filename" />
+            } @else {
+              <div class="media-tile__preview media-tile__preview--file">{{ asset.mimeType }}</div>
+            }
+            <div class="media-tile__meta">
+              <span class="media-tile__filename">{{ asset.filename }}</span>
+              <span class="media-tile__size">{{ formatSize(asset.size) }}</span>
+            </div>
+            <app-button variant="danger" size="sm" [fullWidth]="true" (click)="confirmDelete(asset)">
+              {{ 'mediaLibrary.delete' | translate }}
+            </app-button>
+          </div>
+        </app-card>
+      }
+    </div>
+
+    @if (totalPages() > 1) {
+      <app-pagination [currentPage]="facade.page()" [totalPages]="totalPages()" (pageChange)="facade.setPage($event)" />
+    }
+  }
+
+  <app-dialog
+    [open]="!!pendingDelete()"
+    [titleText]="'mediaLibrary.deleteConfirmTitle' | translate"
+    size="sm"
+    (closed)="cancelDelete()"
+  >
+    <p>{{ 'mediaLibrary.deleteConfirmBody' | translate }}</p>
+    <div class="media-page__dialog-actions">
+      <app-button variant="secondary" (click)="cancelDelete()">{{ 'mediaLibrary.cancel' | translate }}</app-button>
+      <app-button variant="danger" (click)="proceedDelete()">{{ 'mediaLibrary.confirm' | translate }}</app-button>
+    </div>
+  </app-dialog>
+</section>

src/app/features/backoffice/media/media-library-page.component.scss

@@ -0,0 +1,75 @@
+.media-page {
+  display: grid;
+  gap: 16px;
+  padding: 18px;
+}
+
+.media-page__toolbar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  flex-wrap: wrap;
+  gap: 12px;
+}
+
+.media-page__toolbar-actions {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.media-page__grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
+  gap: 12px;
+}
+
+.media-tile {
+  display: grid;
+  gap: 8px;
+}
+
+.media-tile__preview {
+  width: 100%;
+  height: 110px;
+  object-fit: cover;
+  border-radius: var(--radius-md, 6px);
+  background: var(--bg-secondary, #f4f4f5);
+}
+
+.media-tile__preview--file {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: 0.75rem;
+  color: var(--text-secondary, #6b7280);
+  text-align: center;
+  padding: 8px;
+}
+
+.media-tile__meta {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+
+.media-tile__filename {
+  font-size: 0.8125rem;
+  font-weight: 600;
+  color: var(--text-primary, #1f322d);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.media-tile__size {
+  font-size: 0.75rem;
+  color: var(--text-secondary, #6b7280);
+}
+
+.media-page__dialog-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 8px;
+  margin-top: 16px;
+}

src/app/features/backoffice/media/media-library-page.component.ts

@@ -0,0 +1,86 @@
+import { ChangeDetectionStrategy, Component, ElementRef, OnInit, ViewChild, inject, signal } from '@angular/core';
+import { TranslatePipe } from '../../../i18n/translate.pipe';
+import { MediaLibraryFacade } from './facade/media-library.facade';
+import { MediaAsset } from '../../../core/media/models/media-asset.model';
+import { ButtonComponent } from '../../../shared/ui/button/button.component';
+import { InputComponent } from '../../../shared/ui/input/input.component';
+import { CardComponent } from '../../../shared/ui/card/card.component';
+import { EmptyStateComponent } from '../../../shared/ui/empty-state/empty-state.component';
+import { DialogComponent } from '../../../shared/ui/dialog/dialog.component';
+import { PaginationComponent } from '../../../shared/ui/pagination/pagination.component';
+import { SkeletonComponent } from '../../../shared/ui/skeleton/skeleton.component';
+import { FormsModule } from '@angular/forms';
+
+const PAGE_SIZE = 24;
+
+@Component({
+  selector: 'app-media-library-page',
+  standalone: true,
+  imports: [
+    TranslatePipe,
+    FormsModule,
+    ButtonComponent,
+    InputComponent,
+    CardComponent,
+    EmptyStateComponent,
+    DialogComponent,
+    PaginationComponent,
+    SkeletonComponent,
+  ],
+  templateUrl: './media-library-page.component.html',
+  styleUrl: './media-library-page.component.scss',
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+export class MediaLibraryPageComponent implements OnInit {
+  protected readonly facade = inject(MediaLibraryFacade);
+
+  @ViewChild('fileInput') private fileInput?: ElementRef<HTMLInputElement>;
+
+  protected readonly pendingDelete = signal<MediaAsset | null>(null);
+  protected readonly totalPages = () => Math.max(1, Math.ceil(this.facade.total() / PAGE_SIZE));
+
+  ngOnInit(): void {
+    void this.facade.load();
+  }
+
+  protected triggerFileInput(): void {
+    this.fileInput?.nativeElement.click();
+  }
+
+  protected async onFileSelected(event: Event): Promise<void> {
+    const input = event.target as HTMLInputElement;
+    const file = input.files?.[0];
+    input.value = '';
+    if (!file) {
+      return;
+    }
+    await this.facade.upload(file);
+  }
+
+  protected confirmDelete(asset: MediaAsset): void {
+    this.pendingDelete.set(asset);
+  }
+
+  protected cancelDelete(): void {
+    this.pendingDelete.set(null);
+  }
+
+  protected async proceedDelete(): Promise<void> {
+    const asset = this.pendingDelete();
+    if (!asset) {
+      return;
+    }
+    await this.facade.remove(asset.id);
+    this.pendingDelete.set(null);
+  }
+
+  protected formatSize(bytes: number): string {
+    if (bytes < 1024) {
+      return `${bytes} B`;
+    }
+    if (bytes < 1024 * 1024) {
+      return `${(bytes / 1024).toFixed(1)} KB`;
+    }
+    return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
+  }
+}