feat: complete Nexus mission-control workflows

backend/Extensions/ServiceCollectionExtensions.cs

@@ -4,6 +4,7 @@ using Microsoft.AspNetCore.RateLimiting;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
 using Microsoft.IdentityModel.Tokens;
+using ModelContextProtocol.AspNetCore;
 using Nexus.Api.Data;
 using Nexus.Api.Integrations;
 using Nexus.Api.RateLimiting;
@@ -202,6 +203,12 @@ public static class ServiceCollectionExtensions
     /// </summary>
     public static IServiceCollection AddNexusApplicationServices(this IServiceCollection services)
     {
+        services.AddMcpServer()
+            .WithHttpTransport(options => options.Stateless = true)
+            .WithTools<NexusMcpTools>();
+
+        services.AddOptions<StaleTaskRecoveryOptions>()
+            .BindConfiguration(StaleTaskRecoveryOptions.SectionName);
         services.AddHttpContextAccessor();
         services.AddSingleton<LoginAttemptTracker>();
         services.AddTransient<ModelRoutingService>();
@@ -219,6 +226,8 @@ public static class ServiceCollectionExtensions
         services.AddSingleton<ILiveUpdateService, LiveUpdateService>();
         services.AddScoped<INotificationService, NotificationService>();
         services.AddScoped<ICalendarService, CalendarService>();
+        services.AddScoped<IStaleTaskRecoveryService, StaleTaskRecoveryService>();
+        services.AddHostedService<StaleTaskRecoveryBackgroundService>();
 
         // ── Backend Bridge (Agent-Command-Service) ──
         services.AddScoped<ITaskBridgeService, TaskBridgeService>();