feat: add OAuth 2.0 login UI (Google, Yandex, Discord, VK)

- Add OAuthProvider type and extend User.auth_type union
- Add OAuth API methods (providers, authorize, callback)
- Add loginWithOAuth to auth store
- Create OAuthCallback page with state validation
- Create OAuthProviderIcon component with brand SVGs
- Add OAuth buttons to Login page between Telegram and Email
- Add OAuth callback route to App.tsx
- Add translations for ru, en, zh, fa

src/types/index.ts

@@ -12,7 +12,13 @@ export interface User {
   referral_code: string | null;
   language: string;
   created_at: string;
-  auth_type: 'telegram' | 'email'; // Тип аутентификации
+  auth_type: 'telegram' | 'email' | 'google' | 'yandex' | 'discord' | 'vk'; // Тип аутентификации
+}
+
+// OAuth types
+export interface OAuthProvider {
+  name: string;
+  display_name: string;
 }
 
 // Auth types