feat(search/rag): implement NexusSearchBox, dynamic Qdrant collection auto-provisioning, batch vector ingestion, mobile Serilog logging, and resolve 401 auth handler error (#51)

Resolves #52

This Pull Request introduces the **NexusSearchBox** search feature with premium unified styling, implements a robust **dynamic Qdrant collection auto-provisioning and batch-vector ingestion pipeline**, integrates a unified **Serilog logging infrastructure** for the Blazor Hybrid environment (MAUI), and resolves the **401 Unauthorized API header propagation error** inside mobile builds.

### 🚀 Key Implementations

#### 1. Premium `NexusSearchBox` & Semantic Search UI
* **NexusSearchBox Component:** Created an elegant search-as-you-type search box with smooth key navigation, quick-clearing, and seamless dynamic styling.
* **Unified Aesthetics:** Refactored the search box isolated styling to align perfectly with the dashboard's design system using glassmorphism, `--nexus-neon` token gradients, and smooth pulse/fade animations.
* **Semantic Search Integration:** Integrated semantic search query dispatching (`SearchLibrarySemanticallyQuery`) and wired up navigation seamlessly through the updated `ReaderNavigationService`.
* **Tests Hardening:** Added/adapted query assertions in `QueryTests.cs` to guarantee safe parameterization and error boundary mapping.

#### 2. Qdrant Collection Provisioning & Vector Ingestion
* **Dynamic Auto-Provisioning:** Implemented dynamic checking and lazy-creation of the `knowledge_units` collection using 768 dimensions and Cosine distance.
* **High-Performance Ingestion:** Optimized `ProcessKnowledgeUnitsAsync` with high-performance batch embedding generation using `_embeddingGenerator` and deterministic MD5 GUIDs for stable, duplicate-free upsertion.
* **Database Cache Clear Sync:** Integrated Qdrant collection deletion in `ClearCacheAsync` to ensure absolute consistency between the PostgreSQL database cache and vector database indices.

#### 3. Cross-Platform MAUI Logging (Serilog Infrastructure)
* **Serilog Integration:** Configured cross-platform Serilog routing in `SerilogConfiguration.cs`, streaming diagnostic logs safely across native platforms and the Blazor Webview container.
* **Interop Bridge:** Built `BlazorLoggingBridge.cs` to capture web console messages and pipe them directly to the native host logger.
* **Demo Interface:** Added an interactive `SerilogDemo.razor` sandbox under Pages.

#### 4. Resolving 401 Load Errors (Authentication Handler Flow)
* **Authentication Header Handler:** Implemented the `MobileAuthenticationHeaderHandler` to correctly extract, validate, and inject bearer JWT tokens into outbound API requests.
* **Configuration-based API Host:** Structured standard API URI routing to use clean configuration bindings in `appsettings.json`.

---

### 🧪 Verification & Build Status
* Run `dotnet build` from the solution root: Successfully compiled the full multi-targeted solution (`Liczba błędów: 0`).
* All unit and integration tests successfully executed and verified (`dotnet test`).

---------

Co-authored-by: Marek Jasiński <jasins.marek@gmail.com>
Co-authored-by: Marek Jaisński <jasins.marek@gmail.com>
Reviewed-on: #51
Co-authored-by: Antigravity <antigravity@google.com>
Co-committed-by: Antigravity <antigravity@google.com>

src/NexusReader.UI.Shared/Components/Organisms/BookIngestionModal.razor

@@ -2,12 +2,14 @@
 @using NexusReader.Application.Abstractions.Services
 @using NexusReader.Application.Queries.Reader
 @using NexusReader.Application.Commands.Library
+@using NexusReader.UI.Shared.Services
 @using System.Net.Http.Json
 @inject IEpubMetadataExtractor MetadataExtractor
 @inject ILogger<BookIngestionModal> Logger
 @inject HttpClient Http
 @inject IReaderNavigationService ReaderNavigation
 @inject IJSRuntime JSRuntime
+@inject ISyncService SyncService
 @implements IAsyncDisposable
 
 @if (IsOpen)
@@ -16,20 +18,23 @@
         <div class="modal-content glass-panel" @onclick:stopPropagation>
             <div class="modal-header">
                 <h2>Add New Book</h2>
-                <button class="close-btn" @onclick="CloseModal">
-                    <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><line x1="18" y1="6" x2="6" y2="18"></line><line x1="6" y1="6" x2="18" y2="18"></line></svg>
-                </button>
+                @if (!IsIngesting && !IsIndexing)
+                {
+                    <button class="close-btn" @onclick="CloseModal">
+                        <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><line x1="18" y1="6" x2="6" y2="18"></line><line x1="6" y1="6" x2="18" y2="18"></line></svg>
+                    </button>
+                }
             </div>
 
             <div class="modal-body">
-                <div class="parsing-state shimmer" style="@(IsParsing ? "display:flex;" : "display:none;")">
+                <div class="parsing-state shimmer" style="@(IsParsing && !IsIndexing ? "display:flex;" : "display:none;")">
                     <div class="shimmer-content">
                         <div class="spinner"></div>
                         <p>Scanning metadata...</p>
                     </div>
                 </div>
                 
-                <div class="verification-state" style="@(IsVerifying && !IsParsing ? "display:flex;" : "display:none;")">
+                <div class="verification-state" style="@(IsVerifying && !IsParsing && !IsIndexing ? "display:flex;" : "display:none;")">
                     @if (Metadata != null)
                     {
                         <div class="verification-layout">
@@ -74,7 +79,7 @@
                 </div>
                 
                 <div class="upload-state @(_isDragging ? "drag-over" : "")" 
-                     style="@(!IsParsing && !IsVerifying ? "display:flex;" : "display:none;")"
+                     style="@(!IsParsing && !IsVerifying && !IsIndexing ? "display:flex;" : "display:none;")"
                      @ondragenter="OnDragEnter" 
                      @ondragleave="OnDragLeave">
                     <div class="drop-zone">
@@ -87,6 +92,18 @@
                     </div>
                 </div>
 
+                <div class="indexing-state" style="@(IsIndexing ? "display:flex;" : "display:none;")">
+                    <div class="indexing-content">
+                        <div class="spinner"></div>
+                        <h3>Nexus AI Indexing</h3>
+                        <p class="status-msg">@IngestionStatusMessage</p>
+                        <div class="progress-bar-container">
+                            <div class="progress-bar-fill" style="width: @((IngestionProgressPercent * 100).ToString("F0"))%"></div>
+                        </div>
+                        <span class="percent">@((IngestionProgressPercent * 100).ToString("F0"))%</span>
+                    </div>
+                </div>
+
                 
                 @if (!string.IsNullOrEmpty(ErrorMessage))
                 {
@@ -118,15 +135,61 @@
     private bool IsParsing { get; set; }
     private bool IsVerifying { get; set; }
     private bool IsIngesting { get; set; }
+    private bool IsIndexing { get; set; }
+    private string IngestionStatusMessage { get; set; } = "Initializing...";
+    private double IngestionProgressPercent { get; set; }
+    private Guid IngestedBookId { get; set; } = Guid.Empty;
     private LocalEpubMetadata? Metadata { get; set; }
     private string? ErrorMessage { get; set; }
     private byte[]? _epubBytes;
+    private bool _disposed;
     
     // Allow up to 50 MB
     private const long MaxFileSize = 50 * 1024 * 1024;
 
+    protected override async Task OnInitializedAsync()
+    {
+        await SyncService.InitializeAsync();
+        SyncService.OnIngestionProgressReceived += HandleIngestionProgress;
+    }
+
+    private async Task HandleIngestionProgress(string message, double progress)
+    {
+        if (_disposed) return;
+        if (!IsIndexing) return;
+
+        IngestionStatusMessage = message;
+        IngestionProgressPercent = progress;
+        
+        if (!_disposed)
+        {
+            await InvokeAsync(StateHasChanged);
+        }
+
+        if (progress >= 1.0)
+        {
+            // Give the user a moment to see the completion message
+            await Task.Delay(2500);
+            
+            if (_disposed) return;
+
+            // Now close the modal and navigate to the book
+            if (IngestedBookId != Guid.Empty)
+            {
+                var bookId = IngestedBookId;
+                await InvokeAsync(async () => {
+                    if (_disposed) return;
+                    await CloseModal();
+                    ReaderNavigation.NavigateToBook(bookId);
+                });
+            }
+        }
+    }
+
     private async Task CloseModal()
     {
+        if (IsIngesting || IsIndexing) return;
+
         IsOpen = false;
         Reset();
         await IsOpenChanged.InvokeAsync(false);
@@ -137,6 +200,10 @@
         IsParsing = false;
         IsVerifying = false;
         IsIngesting = false;
+        IsIndexing = false;
+        IngestionStatusMessage = "Initializing...";
+        IngestionProgressPercent = 0.0;
+        IngestedBookId = Guid.Empty;
         Metadata = null;
         ErrorMessage = null;
         _isDragging = false;
@@ -168,10 +235,12 @@
             using var stream = file.OpenReadStream(MaxFileSize);
             using var memoryStream = new MemoryStream();
             await stream.CopyToAsync(memoryStream);
+            if (_disposed) return;
             _epubBytes = memoryStream.ToArray();
             
             memoryStream.Position = 0;
             var result = await MetadataExtractor.ExtractMetadataAsync(memoryStream);
+            if (_disposed) return;
 
             if (result.IsSuccess)
             {
@@ -186,12 +255,18 @@
         catch (Exception ex)
         {
             Logger.LogError(ex, "Error uploading EPUB");
-            ErrorMessage = $"An unexpected error occurred: {ex.Message}";
+            if (!_disposed)
+            {
+                ErrorMessage = $"An unexpected error occurred: {ex.Message}";
+            }
         }
         finally
         {
-            IsParsing = false;
-            StateHasChanged();
+            if (!_disposed)
+            {
+                IsParsing = false;
+                StateHasChanged();
+            }
         }
     }
 
@@ -214,39 +289,55 @@
             );
 
             var response = await Http.PostAsJsonAsync("api/library/ingest", request);
+            if (_disposed) return;
 
             if (response.IsSuccessStatusCode)
             {
                 var result = await response.Content.ReadFromJsonAsync<IngestResult>();
+                if (_disposed) return;
                 if (result != null)
                 {
-                    await CloseModal();
-                    ReaderNavigation.NavigateToBook(result.Id);
+                    IngestedBookId = result.Id;
+                    IsVerifying = false;
+                    IsIngesting = false;
+                    IsIndexing = true;
+                    IngestionStatusMessage = "Book saved! Starting background indexing...";
+                    IngestionProgressPercent = 0.0;
+                    StateHasChanged();
                 }
             }
             else
             {
                 ErrorMessage = await response.Content.ReadAsStringAsync();
+                IsIngesting = false;
             }
         }
         catch (Exception ex)
         {
             Logger.LogError(ex, "Error during ingestion");
-            ErrorMessage = "Failed to save book to library. Please try again.";
+            if (!_disposed)
+            {
+                ErrorMessage = "Failed to save book to library. Please try again.";
+                IsIngesting = false;
+            }
         }
         finally
         {
-            IsIngesting = false;
-            StateHasChanged();
+            if (!_disposed)
+            {
+                StateHasChanged();
+            }
         }
     }
 
     private record IngestResult(Guid Id);
 
-    public ValueTask DisposeAsync()
+    public async ValueTask DisposeAsync()
     {
+        _disposed = true;
+        SyncService.OnIngestionProgressReceived -= HandleIngestionProgress;
         // Clear the large byte array so it is eligible for GC even if the component is cached.
         _epubBytes = null;
-        return ValueTask.CompletedTask;
+        await ValueTask.CompletedTask;
     }
 }