Add AddMcpApplicationServices extension method

Extract the duplicated MCP application service registrations
(AuthorizationService, BoardService, ColumnService, CardService,
LabelService, AutomationProposalService, CaptureService,
NotificationService) into a shared extension method that both
MCP stdio and MCP HTTP modes can call.

Part of #951 (DEBT-05).

Author: Chris0Jeky

backend/src/Taskdeck.Api/Extensions/McpApplicationServiceRegistration.cs

@@ -0,0 +1,43 @@
+using Taskdeck.Application.Interfaces;
+using Taskdeck.Application.Services;
+
+namespace Taskdeck.Api.Extensions;
+
+/// <summary>
+/// Registers the minimal subset of Application services required by MCP
+/// resources and tools. Both MCP stdio and MCP HTTP standalone modes call
+/// this instead of the full <see cref="ApplicationServiceRegistration.AddApplicationServices"/>
+/// which includes web-only services (SignalR notifiers, workers, LLM providers, etc.).
+/// </summary>
+public static class McpApplicationServiceRegistration
+{
+    /// <summary>
+    /// Register the Application services that MCP resources and tools depend on.
+    /// Deliberately skips web-only services (SignalR notifiers, workers,
+    /// LLM providers, rate limiting, etc.) to keep the MCP host minimal.
+    /// </summary>
+    public static IServiceCollection AddMcpApplicationServices(this IServiceCollection services)
+    {
+        services.AddScoped<AuthorizationService>();
+        services.AddScoped<IAuthorizationService>(
+            sp => sp.GetRequiredService<AuthorizationService>());
+        services.AddScoped<BoardService>(sp =>
+            new BoardService(
+                sp.GetRequiredService<IUnitOfWork>(),
+                sp.GetRequiredService<IAuthorizationService>()));
+        services.AddScoped<ColumnService>();
+        services.AddScoped<CardService>();
+        services.AddScoped<LabelService>();
+        services.AddScoped<AutomationProposalService>();
+        services.AddScoped<IAutomationProposalService>(
+            sp => sp.GetRequiredService<AutomationProposalService>());
+        services.AddScoped<CaptureService>();
+        services.AddScoped<ICaptureService>(
+            sp => sp.GetRequiredService<CaptureService>());
+        services.AddScoped<NotificationService>();
+        services.AddScoped<INotificationService>(
+            sp => sp.GetRequiredService<NotificationService>());
+
+        return services;
+    }
+}