Remove BTCPay completely, integrate SilverPAY only, configure TeleBot with real token

- Removed all BTCPay references from services and configuration
- Implemented SilverPAY as sole payment provider (no fallback)
- Fixed JWT authentication with proper key length (256+ bits)
- Added UsersController with full CRUD operations
- Updated User model with Email and Role properties
- Configured TeleBot with real Telegram bot token
- Fixed launchSettings.json with JWT environment variable
- E2E tests passing for authentication, catalog, orders
- Payment creation pending SilverPAY server fix

🤖 Generated with Claude Code

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

LittleShop/Services/ICryptoPaymentService.cs

@@ -8,5 +8,6 @@ public interface ICryptoPaymentService
     Task<CryptoPaymentDto> CreatePaymentAsync(Guid orderId, CryptoCurrency currency);
     Task<IEnumerable<CryptoPaymentDto>> GetPaymentsByOrderAsync(Guid orderId);
     Task<bool> ProcessPaymentWebhookAsync(string invoiceId, PaymentStatus status, decimal amount, string? transactionHash = null);
+    Task<bool> ProcessSilverPayWebhookAsync(string orderId, PaymentStatus status, decimal amount, string? transactionHash = null, int confirmations = 0);
     Task<PaymentStatusDto> GetPaymentStatusAsync(Guid paymentId);
 }