added translation

src/app/services/language.service.ts

@@ -0,0 +1,34 @@
+import { Injectable, signal } from '@angular/core';
+import { TRANSLATIONS } from '../i18n/translations';
+
+export type SupportedLang = 'en' | 'ru';
+
+export const SUPPORTED_LANGS: { code: SupportedLang; label: string }[] = [
+  { code: 'en', label: 'EN' },
+  { code: 'ru', label: 'RU' },
+];
+
+// All UI strings live in src/app/i18n/translations.ts
+
+@Injectable({ providedIn: 'root' })
+export class LanguageService {
+  currentLang = signal<SupportedLang>('ru');
+
+  toggle() {
+    this.currentLang.set(this.currentLang() === 'en' ? 'ru' : 'en');
+  }
+
+  setLang(lang: SupportedLang) {
+    this.currentLang.set(lang);
+  }
+
+  t(key: string): string {
+    const lang = this.currentLang();
+    return TRANSLATIONS[lang]?.[key] ?? TRANSLATIONS['en']?.[key] ?? key;
+  }
+
+  /** Returns the secondary content language (the one to translate INTO). */
+  get contentTranslationLang(): SupportedLang {
+    return this.currentLang() === 'en' ? 'ru' : 'en';
+  }
+}