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/Models/CryptoPayment.cs

@@ -27,7 +27,10 @@ public class CryptoPayment
     
     [StringLength(200)]
     public string? BTCPayInvoiceId { get; set; }
-    
+
+    [StringLength(200)]
+    public string? SilverPayOrderId { get; set; }
+
     [StringLength(200)]
     public string? TransactionHash { get; set; }