Refactor: Web Consolidation and Identity Stabilization (#40)

## Overview
This PR completes the architectural consolidation of the web project and stabilizes the Identity-based authentication flow for the NexusReader application. It also refines the UI aesthetic for the Book Ingestion Modal as requested in #33.

## Key Changes
- **Project Consolidation**: Fully merged `NexusReader.Web.New` into `NexusReader.Web`. This includes updating all namespace references, VS Code launch/task configurations, and CI/CD (`Dockerfile`).
- **Identity Stabilization**:
  - Implemented `IIdentityService` on the server using `SignInManager<NexusUser>` and `UserManager<NexusUser>`.
  - Fixed registration logic to include mandatory fields (`SubscriptionPlanId`, `TenantId`).
  - Updated `Login.razor` to force a page reload on successful login, ensuring proper synchronization of authentication cookies between SignalR and the browser.
- **UI/UX Refinement**:
  - Updated `BookIngestionModal` styling to follow the **Nexus Neon** design system.
  - Added premium button styles with hover effects and glows.
  - Improved modal layout and interaction feedback (shimmer effects, spinner colors).
- **Cleanup**: Removed obsolete interfaces and constants that were superseded by newer Application layer implementations.

## Verification
- Successfully built the solution: `dotnet build NexusReader.slnx --no-restore`
- Verified project structure and file moves.
- Validated server-side authentication logic.

Fixes #33

---------

Co-authored-by: Marek Jasiński <jasins.marek@gmail.com>
Reviewed-on: #40
Co-authored-by: Antigravity <antigravity@google.com>
Co-committed-by: Antigravity <antigravity@google.com>

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

@@ -2,13 +2,17 @@ using System.Security.Claims;
 using System.Text.Json;
 using Microsoft.AspNetCore.Components.Authorization;
 using NexusReader.Application.Abstractions.Services;
-using NexusReader.UI.Shared.Constants;
+using NexusReader.Application.Constants;
 
 namespace NexusReader.UI.Shared.Services;
 
 public class NexusAuthenticationStateProvider : AuthenticationStateProvider
 {
     private readonly INativeStorageService _storageService;
+    
+    // SECURITY NOTE: We currently store roles in local storage to persist state across refreshes.
+    // In a production SaaS environment, consider using ProtectedBrowserStorage (Blazor Server) 
+    // or encrypted storage/JWT claims validation to prevent client-side role tampering.
     private const string TokenKey = StorageKeys.AuthToken;
 
     public NexusAuthenticationStateProvider(INativeStorageService storageService)
@@ -38,10 +42,15 @@ public class NexusAuthenticationStateProvider : AuthenticationStateProvider
             {
                 var emailResult = await _storageService.GetSecureString(StorageKeys.UserEmail);
                 var tenantIdResult = await _storageService.GetSecureString(StorageKeys.UserTenant);
+                var rolesResult = await _storageService.GetSecureString(StorageKeys.UserRoles);
 
                 if (emailResult.IsSuccess && !string.IsNullOrEmpty(emailResult.Value))
                 {
-                    _cachedState = CreateState(emailResult.Value, tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", "OpaqueBearer");
+                    _cachedState = CreateState(
+                        emailResult.Value, 
+                        tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", 
+                        "OpaqueBearer",
+                        rolesResult.IsSuccess ? rolesResult.Value! : "");
                     return _cachedState;
                 }
             }
@@ -51,7 +60,12 @@ public class NexusAuthenticationStateProvider : AuthenticationStateProvider
             if (storedEmailResult.IsSuccess && !string.IsNullOrEmpty(storedEmailResult.Value))
             {
                 var tenantIdResult = await _storageService.GetSecureString(StorageKeys.UserTenant);
-                _cachedState = CreateState(storedEmailResult.Value, tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", "CookieAuth");
+                var rolesResult = await _storageService.GetSecureString(StorageKeys.UserRoles);
+                _cachedState = CreateState(
+                    storedEmailResult.Value, 
+                    tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", 
+                    "CookieAuth",
+                    rolesResult.IsSuccess ? rolesResult.Value! : "");
                 return _cachedState;
             }
 
@@ -67,7 +81,7 @@ public class NexusAuthenticationStateProvider : AuthenticationStateProvider
         }
     }
 
-    private AuthenticationState CreateState(string email, string tenantId, string authType)
+    private AuthenticationState CreateState(string email, string tenantId, string authType, string rolesStr = "")
     {
         var claims = new List<Claim>
         {
@@ -75,13 +89,23 @@ public class NexusAuthenticationStateProvider : AuthenticationStateProvider
             new Claim(ClaimTypes.Email, email),
             new Claim("TenantId", tenantId)
         };
+        
+        if (!string.IsNullOrEmpty(rolesStr))
+        {
+            var roles = rolesStr.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
+            foreach (var role in roles)
+            {
+                claims.Add(new Claim(ClaimTypes.Role, role.Trim()));
+            }
+        }
+        
         var identity = new ClaimsIdentity(claims, authType);
         return new AuthenticationState(new ClaimsPrincipal(identity));
     }
 
-    public void NotifyUserAuthentication(string email, string tenantId)
+    public void NotifyUserAuthentication(string email, string tenantId, string rolesStr = "")
     {
-        _cachedState = CreateState(email, tenantId, "OpaqueBearer");
+        _cachedState = CreateState(email, tenantId, "OpaqueBearer", rolesStr);
         NotifyAuthenticationStateChanged(Task.FromResult(_cachedState));
     }