feat: client-side currency conversion with admin-configurable rates

- CurrencyRatesService: RUB-based rates, persisted via localStorage
- CurrencyConvertPipe: impure pipe converting item price to selected currency
- Admin settings page: editable currency rates form
- Applied conversion to product-card, product-information, quick-view-dialog,
  delivery-information, compare-table, cart totals + payment payload

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/features/admin/settings/pages/admin-settings-page.component.html

@@ -11,4 +11,25 @@
       <span>{{ 'adminSettings.densityCompact' | translate }}</span>
     </label>
   </div>
+
+  <div class="settings-card">
+    <h2>{{ 'adminSettings.currencyRates' | translate }}</h2>
+    <p class="settings-explain">{{ 'adminSettings.currencyRatesExplain' | translate }}</p>
+    <div class="rate-row" *ngFor="let currency of languageService.currencies">
+      <span class="rate-code">{{ currency.code }}</span>
+      <input
+        class="rate-input"
+        type="number"
+        min="0"
+        step="0.0001"
+        [disabled]="currency.code === currencyRates.baseCurrency"
+        [ngModel]="rateDrafts()[currency.code]"
+        (ngModelChange)="onRateInput(currency.code, $event)"
+      />
+    </div>
+    <div class="rate-actions">
+      <button type="button" class="save-button" (click)="saveRates()">{{ 'adminSettings.currencyRatesSave' | translate }}</button>
+      <span class="saved-message" *ngIf="showSavedMessage()">{{ 'adminSettings.currencyRatesSaved' | translate }}</span>
+    </div>
+  </div>
 </section>

src/app/features/admin/settings/pages/admin-settings-page.component.scss

@@ -12,3 +12,25 @@
 .settings-explain { margin: 0; color: var(--text-secondary, #6b7280); font-size: var(--font-size-sm, 0.8125rem); }
 
 .toggle-row { display: flex; align-items: center; gap: 8px; font-weight: var(--font-weight-normal, 400); }
+
+.rate-row { display: flex; align-items: center; gap: 12px; }
+.rate-code { width: 48px; font-weight: var(--font-weight-medium, 500); }
+.rate-input {
+  width: 120px;
+  padding: 6px 8px;
+  border: 1px solid var(--border-color, #d3dad9);
+  border-radius: var(--radius-sm, 4px);
+  background: var(--bg-primary, #fff);
+}
+.rate-input:disabled { opacity: 0.6; }
+
+.rate-actions { display: flex; align-items: center; gap: 12px; margin-top: 4px; }
+.save-button {
+  padding: 8px 16px;
+  border: none;
+  border-radius: var(--radius-sm, 4px);
+  background: var(--color-primary, #16a34a);
+  color: #fff;
+  cursor: pointer;
+}
+.saved-message { color: var(--color-success, #16a34a); font-size: var(--font-size-sm, 0.8125rem); }

src/app/features/admin/settings/pages/admin-settings-page.component.ts

@@ -1,21 +1,47 @@
-import { ChangeDetectionStrategy, Component, inject } from '@angular/core';
+import { ChangeDetectionStrategy, Component, inject, signal } from '@angular/core';
+import { CommonModule } from '@angular/common';
 import { FormsModule } from '@angular/forms';
 import { AdminPreferencesService } from '../services/admin-preferences.service';
 import { TranslatePipe } from '../../../../i18n/translate.pipe';
 import { ToggleComponent } from '../../../../shared/ui/toggle/toggle.component';
+import { CurrencyRatesService } from '../../../../services/currency-rates.service';
+import { LanguageService } from '../../../../services/language.service';
+
+const SAVED_MESSAGE_DURATION_MS = 2000;
 
 @Component({
   selector: 'app-admin-settings-page',
   standalone: true,
-  imports: [FormsModule, TranslatePipe, ToggleComponent],
+  imports: [CommonModule, FormsModule, TranslatePipe, ToggleComponent],
   templateUrl: './admin-settings-page.component.html',
   styleUrls: ['./admin-settings-page.component.scss'],
   changeDetection: ChangeDetectionStrategy.OnPush
 })
 export class AdminSettingsPageComponent {
   readonly preferences = inject(AdminPreferencesService);
+  readonly currencyRates = inject(CurrencyRatesService);
+  readonly languageService = inject(LanguageService);
+
+  readonly rateDrafts = signal<Record<string, number>>({ ...this.currencyRates.rates() });
+  readonly showSavedMessage = signal(false);
 
   onCompactToggle(compact: boolean): void {
     this.preferences.setDensity(compact ? 'compact' : 'comfortable');
   }
+
+  onRateInput(code: string, value: string): void {
+    const parsed = Number(value);
+    this.rateDrafts.set({ ...this.rateDrafts(), [code]: parsed });
+  }
+
+  saveRates(): void {
+    for (const currency of this.languageService.currencies) {
+      const rate = this.rateDrafts()[currency.code];
+      if (Number.isFinite(rate) && rate > 0) {
+        this.currencyRates.setRate(currency.code, rate);
+      }
+    }
+    this.showSavedMessage.set(true);
+    setTimeout(() => this.showSavedMessage.set(false), SAVED_MESSAGE_DURATION_MS);
+  }
 }