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- **Cleanup**: Removed obsolete interfaces and constants that were superseded by newer Application layer implementations.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/Pages/Account/Login.razor

@@ -6,6 +6,7 @@
 @using NexusReader.UI.Shared.Components.Atoms
 @inject IIdentityService IdentityService
 @inject NavigationManager NavigationManager
+@inject IJSRuntime JS
 
 <div class="login-page-container">
     <div class="mesh-bg"></div>
@@ -90,6 +91,12 @@
     </div>
 </div>
 
+<form id="nexusLoginForm" method="post" action="/account/login-form" style="display:none">
+    <input type="hidden" name="email" value="@_loginModel.Email" />
+    <input type="hidden" name="password" value="@_loginModel.Password" />
+    <input type="hidden" name="rememberMe" value="@(_loginModel.RememberMe ? "true" : "false")" />
+</form>
+
 @code {
     [Parameter]
     [SupplyParameterFromQuery(Name = "error")]
@@ -125,7 +132,8 @@
             var result = await IdentityService.LoginAsync(_loginModel.Email, _loginModel.Password, _loginModel.RememberMe);
             if (result.IsSuccess) 
             {
-                NavigationManager.NavigateTo("/");
+                // Trigger hidden form submission to perform cookie-based sign-in
+                await JS.InvokeVoidAsync("eval", "document.getElementById('nexusLoginForm').submit()");
             }
             else 
             {

src/NexusReader.UI.Shared/Pages/Account/Profile.razor

@@ -106,7 +106,7 @@
 </div>
 
 @code {
-    private UserProfile? _profile;
+    private UserProfileDto? _profile;
 
     protected override async Task OnInitializedAsync()
     {
@@ -133,6 +133,6 @@
     private async Task HandleLogout()
     {
         await IdentityService.LogoutAsync();
-        NavigationManager.NavigateTo("/account/login");
+        NavigationManager.NavigateTo("/account/logout-form", true);
     }
 }

src/NexusReader.UI.Shared/Pages/Account/Register.razor

@@ -6,6 +6,7 @@
 @using NexusReader.UI.Shared.Components.Atoms
 @inject IIdentityService IdentityService
 @inject NavigationManager NavigationManager
+@inject IJSRuntime JS
 
 <div class="login-page-container">
     <div class="mesh-bg"></div>
@@ -69,6 +70,12 @@
     </div>
 </div>
 
+<form id="nexusLoginForm" method="post" action="/account/login-form" style="display:none">
+    <input type="hidden" name="email" value="@_registerModel.Email" />
+    <input type="hidden" name="password" value="@_registerModel.Password" />
+    <input type="hidden" name="rememberMe" value="false" />
+</form>
+
 @code {
     private RegisterModel _registerModel = new();
     private string? _errorMessage;
@@ -87,7 +94,8 @@
                 var loginResult = await IdentityService.LoginAsync(_registerModel.Email, _registerModel.Password);
                 if (loginResult.IsSuccess) 
                 {
-                    NavigationManager.NavigateTo("/");
+                    // Trigger hidden form submission to perform cookie-based sign-in
+                    await JS.InvokeVoidAsync("eval", "document.getElementById('nexusLoginForm').submit()");
                 }
                 else 
                 {

src/NexusReader.UI.Shared/Pages/Dashboard.razor

@@ -134,7 +134,7 @@
 </div>
 
 @code {
-    private UserProfile? _profile;
+    private UserProfileDto? _profile;
 
     protected override async Task OnInitializedAsync()
     {

src/NexusReader.UI.Shared/Pages/Library.razor

@@ -1,16 +1,19 @@
 @page "/library"
 @attribute [Authorize]
+@using NexusReader.UI.Shared.Components.Organisms
 
 <div class="library-page">
     <header class="library-header">
         <h1>Biblioteka</h1>
         <AuthorizeView Roles="Admin, ContentManager">
-            <NexusButton Class="add-book-trigger">
+            <NexusButton Class="add-book-trigger" OnClick="() => _isModalOpen = true">
                 [+] Add New Book
             </NexusButton>
         </AuthorizeView>
     </header>
     
+    <BookIngestionModal @bind-IsOpen="_isModalOpen" />
+    
     <div class="library-content glass-panel">
         <div class="empty-state">
             <p>Twoja kolekcja książek i dokumentów pojawi się tutaj wkrótce.</p>
@@ -51,3 +54,7 @@
         opacity: 0.6;
     }
 </style>
+
+@code {
+    private bool _isModalOpen;
+}