refactor: consolidate project structure by migrating authentication, identity, and shared UI components while removing legacy Web Client files.

src/NexusReader.Infrastructure/DependencyInjection.cs

@@ -10,6 +10,10 @@ using NexusReader.Infrastructure.Services;
 using NexusReader.Infrastructure.Configuration;
 using Polly;
 using Polly.Retry;
+using NexusReader.Domain.Entities;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Authorization;
+using NexusReader.Application.Security.Authorization;
 
 namespace NexusReader.Infrastructure;
 
@@ -53,6 +57,14 @@ public static class DependencyInjection
         services.AddScoped<IKnowledgeService, KnowledgeService>();
         services.AddTransient<IAiGenerateQuizService, FakeAiGenerateQuizService>();
         services.AddTransient<IEpubService, EpubService>();
+
+        services.AddAuthorizationCore(options =>
+        {
+            options.AddPolicy("ProUser", policy => policy.Requirements.Add(new ProUserRequirement()));
+        });
+
+        services.AddScoped<IAuthorizationHandler, ProUserHandler>();
+
         return services;
     }
 }