feat: add i18n and avatar upload

apps/frontend/src/components/LanguageSwitcher.tsx

@@ -0,0 +1,41 @@
+import { Languages } from 'lucide-react';
+import { useI18n, type Language } from '@/i18n/i18n';
+import { cn } from '@/lib/cn';
+
+const languages: Array<{ value: Language; label: string }> = [
+  { value: 'ru', label: 'RU' },
+  { value: 'en', label: 'EN' },
+];
+
+export function LanguageSwitcher({ className }: { className?: string }) {
+  const { language, setLanguage, t } = useI18n();
+
+  return (
+    <div
+      className={cn(
+        'inline-flex items-center gap-1 rounded-md border border-border bg-surface/90 p-1 text-xs shadow-card',
+        className,
+      )}
+      aria-label={t('language.switch')}
+    >
+      <Languages className="ml-1 h-3.5 w-3.5 text-muted" aria-hidden />
+      {languages.map((item) => (
+        <button
+          key={item.value}
+          type="button"
+          onClick={() => setLanguage(item.value)}
+          className={cn(
+            'rounded px-2 py-1 font-semibold transition-colors',
+            language === item.value
+              ? 'bg-primary text-primary-foreground'
+              : 'text-muted hover:bg-surface-muted hover:text-ink',
+          )}
+          aria-pressed={language === item.value}
+          title={item.value === 'ru' ? t('language.ru') : t('language.en')}
+        >
+          {item.label}
+        </button>
+      ))}
+    </div>
+  );
+}