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

src/NexusReader.UI.Shared/Services/IdentityService.cs

@@ -0,0 +1,87 @@
+using System.Net.Http.Json;
+using NexusReader.Application.Abstractions.Services;
+
+namespace NexusReader.UI.Shared.Services;
+
+public interface IIdentityService
+{
+    Task<bool> RegisterAsync(string email, string password);
+    Task<bool> LoginAsync(string email, string password);
+    Task LogoutAsync();
+    Task<UserProfile?> GetProfileAsync();
+}
+
+public record UserProfile(
+    string Email, 
+    int AITokenLimit, 
+    int AITokensUsed, 
+    string CurrentPlan, 
+    Guid TenantId);
+
+public class IdentityService : IIdentityService
+{
+    private readonly HttpClient _httpClient;
+    private readonly INativeStorageService _storageService;
+    private readonly NexusAuthenticationStateProvider _authStateProvider;
+    private const string TokenKey = "nexus_auth_token";
+
+    public IdentityService(
+        HttpClient httpClient, 
+        INativeStorageService storageService, 
+        NexusAuthenticationStateProvider authStateProvider)
+    {
+        _httpClient = httpClient;
+        _storageService = storageService;
+        _authStateProvider = authStateProvider;
+    }
+
+    public async Task<bool> RegisterAsync(string email, string password)
+    {
+        var response = await _httpClient.PostAsJsonAsync("identity/register", new { email, password });
+        return response.IsSuccessStatusCode;
+    }
+
+    public async Task<bool> LoginAsync(string email, string password)
+    {
+        var response = await _httpClient.PostAsJsonAsync("identity/login", new { email, password });
+
+        if (response.IsSuccessStatusCode)
+        {
+            var result = await response.Content.ReadFromJsonAsync<LoginResponse>();
+            if (result != null && !string.IsNullOrEmpty(result.AccessToken))
+            {
+                await _storageService.SaveSecureString(TokenKey, result.AccessToken);
+                _authStateProvider.NotifyUserAuthentication(result.AccessToken);
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public async Task LogoutAsync()
+    {
+        _storageService.RemoveSecure(TokenKey);
+        _authStateProvider.NotifyUserLogout();
+    }
+    
+    public async Task<UserProfile?> GetProfileAsync()
+    {
+        try
+        {
+            return await _httpClient.GetFromJsonAsync<UserProfile>("identity/profile");
+        }
+        catch
+        {
+            return null;
+        }
+    }
+
+    private class LoginResponse
+    {
+        public string TokenType { get; set; } = string.Empty;
+        public string AccessToken { get; set; } = string.Empty;
+        public int ExpiresIn { get; set; }
+        public string RefreshToken { get; set; } = string.Empty;
+    }
+}