Add real-time dashboard updates with SignalR

Integrate SignalR to provide real-time dashboard update notifications.
- Added DashboardsHub and DashboardChangeNotifier on the backend.
- Modified SqlDashboardStorage to trigger notifications on changes.
- Registered SignalR services and mapped the hub endpoint.
- Updated Blazor clients to connect to the hub and refresh dashboards on change.
- Added SignalR client packages and necessary DI/configuration.

DbFirst.API/Program.cs

@@ -1,5 +1,6 @@
 using DbFirst.API.Middleware;
 using DbFirst.API.Dashboards;
+using DbFirst.API.Hubs;
 using DbFirst.Application;
 using DbFirst.Application.Repositories;
 using DbFirst.Domain;
@@ -53,6 +54,8 @@ builder.Services.AddApplication();
 builder.Services.AddScoped<ICatalogRepository, CatalogRepository>();
 
 builder.Services.AddDevExpressControls();
+builder.Services.AddSignalR();
+builder.Services.AddSingleton<IDashboardChangeNotifier, DashboardChangeNotifier>();
 builder.Services.AddScoped<DashboardConfigurator>((IServiceProvider serviceProvider) => {
     var dashboardsPath = Path.Combine(builder.Environment.ContentRootPath, "Data", "Dashboards");
     Directory.CreateDirectory(dashboardsPath);
@@ -112,7 +115,8 @@ builder.Services.AddScoped<DashboardConfigurator>((IServiceProvider serviceProvi
     DashboardConfigurator configurator = new DashboardConfigurator();
 
     var connectionString = builder.Configuration.GetConnectionString("DefaultConnection") ?? string.Empty;
-    var dashboardStorage = new SqlDashboardStorage(connectionString, "TBDD_SMF_CONFIG");
+    var notifier = serviceProvider.GetRequiredService<IDashboardChangeNotifier>();
+    var dashboardStorage = new SqlDashboardStorage(connectionString, "TBDD_SMF_CONFIG", notifier: notifier);
     configurator.SetDashboardStorage(dashboardStorage);
 
     DataSourceInMemoryStorage dataSourceStorage = new DataSourceInMemoryStorage();
@@ -155,7 +159,7 @@ app.UseCors();
 app.UseAuthorization();
 
 app.MapDashboardRoute("api/dashboard", "DefaultDashboard");
-
+app.MapHub<DashboardsHub>("/hubs/dashboards");
 app.MapControllers();
 
 app.Run();