CUB-53: add SignalR hub registration and configuration

backend/Program.cs

@@ -0,0 +1,24 @@
+using ControlCenter.Api.Hubs;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Add services to the container.
+builder.Services.AddOpenApi();
+
+// Register SignalR for real-time agent status updates
+builder.Services.AddSignalR();
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline.
+if (app.Environment.IsDevelopment())
+{
+    app.MapOpenApi();
+}
+
+app.UseHttpsRedirection();
+
+// Map SignalR hub endpoint
+app.MapHub<AgentStatusHub>("/hub");
+
+app.Run();