Add: SignalR real-time notifications for admin panel

- Created NotificationHub for instant browser notifications
- Updated CryptoPaymentService to broadcast via SignalR
- Added JavaScript client with toast notifications
- Works with custom SSL certificates (no FCM dependency)
- Automatic reconnection with exponential backoff
- Notification sound and visual indicators
- Bypasses all Web Push SSL certificate issues

LittleShop/Services/CryptoPaymentService.cs

@@ -1,8 +1,10 @@
 using Microsoft.EntityFrameworkCore;
+using Microsoft.AspNetCore.SignalR;
 using LittleShop.Data;
 using LittleShop.Models;
 using LittleShop.DTOs;
 using LittleShop.Enums;
+using LittleShop.Hubs;
 
 namespace LittleShop.Services;
 
@@ -14,6 +16,7 @@ public class CryptoPaymentService : ICryptoPaymentService
     private readonly IConfiguration _configuration;
     private readonly IPushNotificationService _pushNotificationService;
     private readonly ITeleBotMessagingService _teleBotMessagingService;
+    private readonly IHubContext<NotificationHub> _notificationHub;
 
     public CryptoPaymentService(
         LittleShopContext context,
@@ -21,7 +24,8 @@ public class CryptoPaymentService : ICryptoPaymentService
         ILogger<CryptoPaymentService> logger,
         IConfiguration configuration,
         IPushNotificationService pushNotificationService,
-        ITeleBotMessagingService teleBotMessagingService)
+        ITeleBotMessagingService teleBotMessagingService,
+        IHubContext<NotificationHub> notificationHub)
     {
         _context = context;
         _silverPayService = silverPayService;
@@ -29,8 +33,9 @@ public class CryptoPaymentService : ICryptoPaymentService
         _configuration = configuration;
         _pushNotificationService = pushNotificationService;
         _teleBotMessagingService = teleBotMessagingService;
+        _notificationHub = notificationHub;
 
-        _logger.LogInformation("CryptoPaymentService initialized with SilverPAY");
+        _logger.LogInformation("CryptoPaymentService initialized with SilverPAY and SignalR notifications");
     }
 
     public async Task<CryptoPaymentDto> CreatePaymentAsync(Guid orderId, CryptoCurrency currency)
@@ -215,13 +220,26 @@ public class CryptoPaymentService : ICryptoPaymentService
             var title = "💰 Payment Confirmed";
             var body = $"Order #{orderId.ToString()[..8]} payment of £{amount:F2} confirmed. Ready for acceptance.";
 
-            // Send push notification to admin users
+            // Send SignalR real-time notification to connected admin users
+            await _notificationHub.Clients.All.SendAsync("ReceiveNotification", new
+            {
+                title = title,
+                message = body,
+                type = "payment",
+                orderId = orderId,
+                amount = amount,
+                timestamp = DateTime.UtcNow,
+                icon = "💰",
+                url = $"/Admin/Orders/Details/{orderId}"
+            });
+
+            // Send push notification to admin users (may not work with custom CA)
             await _pushNotificationService.SendOrderNotificationAsync(orderId, title, body);
 
             // Send TeleBot message to customer
             await _teleBotMessagingService.SendPaymentConfirmedAsync(orderId);
 
-            _logger.LogInformation("Sent payment confirmation notifications for order {OrderId} (Admin + Customer)", orderId);
+            _logger.LogInformation("Sent payment confirmation notifications for order {OrderId} (SignalR + Push + Telegram)", orderId);
         }
         catch (Exception ex)
         {