improve: performance

src/app/services/language-preference.service.ts

@@ -0,0 +1,35 @@
+import { Injectable, signal } from '@angular/core';
+
+import type { LanguageCode } from '../../languages/language.types';
+
+@Injectable({ providedIn: 'root' })
+export class LanguagePreferenceService {
+  private static readonly storageKey = 'portfolio-language';
+  private readonly currentLanguageCode = signal<LanguageCode>('en');
+  private readonly languageConfirmed = signal(true);
+
+  readonly languageCode = this.currentLanguageCode.asReadonly();
+  readonly isLanguageConfirmed = this.languageConfirmed.asReadonly();
+
+  initializeFromStorage(): LanguageCode {
+    if (typeof window === 'undefined') {
+      return this.currentLanguageCode();
+    }
+
+    const storedLanguage = window.localStorage.getItem(LanguagePreferenceService.storageKey);
+    if (storedLanguage === 'de' || storedLanguage === 'en') {
+      this.currentLanguageCode.set(storedLanguage);
+    }
+
+    return this.currentLanguageCode();
+  }
+
+  confirmLanguage(code: LanguageCode): void {
+    this.currentLanguageCode.set(code);
+    this.languageConfirmed.set(true);
+
+    if (typeof window !== 'undefined') {
+      window.localStorage.setItem(LanguagePreferenceService.storageKey, code);
+    }
+  }
+}