feat: Ingestion Pipeline Stabilization and WASM Service Proxies (#42)

This PR stabilizes the Nexus Ingestion Engine by implementing functional service proxies for the Blazor WASM client and refining the backend infrastructure for real-time progress tracking and database compatibility.

### Key Changes
- **Infrastructure Stabilization**:
  - Implemented production-grade `EbookRepository` with PostgreSQL `EF.Functions.ILike` support.
  - Enforced `IsReadyForReading = false` state for newly added ebooks (resolves #35).
  - Updated `SignalRSyncBroadcaster` to support targeted user messaging and ingestion-specific progress updates (resolves #37).
- **WASM Client Functional Proxies**:
  - Replaced "Throwing" dummy services with `WasmEbookRepository`, `WasmSyncBroadcaster`, `WasmBookStorageService`, and `WasmEmbeddingGenerator`.
  - These services proxy requests to the backend via a new set of Minimal API endpoints in `NexusReader.Web`.
- **Domain Refinement**:
  - Added `IsReadyForReading` flag to the `Ebook` entity to manage background AI processing states.

### Related Issues
- Fixes #35
- Fixes #36
- Fixes #37

---------

Co-authored-by: Marek Jasiński <jasins.marek@gmail.com>
Reviewed-on: #42
Co-authored-by: Antigravity <antigravity@google.com>
Co-committed-by: Antigravity <antigravity@google.com>

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

@@ -2,6 +2,7 @@
 @using NexusReader.Application.Queries.Reader
 @using Microsoft.JSInterop
 @using NexusReader.UI.Shared.Services
+@using Microsoft.AspNetCore.Components.Authorization
 @implements IDisposable
 @inject IMediator Mediator
 @inject IJSRuntime JS
@@ -11,8 +12,8 @@
 @inject KnowledgeCoordinator Coordinator
 @inject IReaderInteractionService InteractionService
 @inject ISyncService SyncService
-@using Microsoft.AspNetCore.Components.Authorization
 @inject AuthenticationStateProvider AuthStateProvider
+@inject ILogger<ReaderCanvas> Logger
 
 <div class="reader-canvas @(ThemeService.IsLightMode ? "theme-light" : "theme-dark")">
     @if (ViewModel == null)
@@ -59,7 +60,7 @@
         await Coordinator.ClearAsync();
         ThemeService.OnThemeChanged += HandleUpdate;
         NavigationService.OnNavigationChanged += OnNavigationChanged;
-        
+
         InteractionService.OnScrollToBlockRequested += HandleScrollRequested;
         InteractionService.OnHighlightBlockRequested += HandleHighlightRequested;
         InteractionService.OnTextSelected += HandleTextSelected;
@@ -102,7 +103,10 @@
             var module = await JS.InvokeAsync<IJSObjectReference>("import", "./_content/NexusReader.UI.Shared/js/selectionHandler.js");
             await module.InvokeVoidAsync("initSelectionListener", DotNetObjectReference.Create(this), _containerRef);
         }
-        catch { }
+        catch (Exception ex)
+        {
+            Logger.LogWarning(ex, "Failed to initialize JS selection listener. Text selection will be unavailable.");
+        }
     }
 
     private async Task InitializeObserverAsync()
@@ -112,24 +116,25 @@
             var module = await JS.InvokeAsync<IJSObjectReference>("import", "./_content/NexusReader.UI.Shared/js/readerObserver.js");
             await module.InvokeVoidAsync("initObserver", DotNetObjectReference.Create(this), ".reader-flow-container", ".block-wrapper");
         }
-        catch { }
+        catch (Exception ex)
+        {
+            Logger.LogWarning(ex, "Failed to initialize JS scroll observer. Reading progress sync will be unavailable.");
+        }
     }
 
     [JSInvokable]
     public async Task HandleBlockReached(string blockId, string content)
     {
         await Coordinator.OnBlockReachedAsync(blockId, content);
-        
+
         if (ViewModel != null)
         {
-            // Calculate progress: (CurrentChapter / TotalChapters) * 100 
-            // Simple approximation for now: chapter-based
             double progress = ((double)(ViewModel.CurrentChapterIndex + 1) / ViewModel.TotalChapters) * 100;
-            
+
             await SyncService.UpdateProgressAsync(
-                blockId, 
-                ViewModel.EbookId, 
-                progress, 
+                blockId,
+                ViewModel.EbookId,
+                progress,
                 ViewModel.ChapterTitle,
                 ViewModel.CurrentChapterIndex);
         }
@@ -137,10 +142,8 @@
 
     private async Task HandleSyncProgressReceived(string blockId, DateTime timestamp)
     {
-        // For now, let's just scroll to the node if it's in the current view, 
-        // or just log it. Usually, we should prompt the user.
-        Console.WriteLine($"[Sync] Received progress from another device: {blockId} at {timestamp}");
-        
+        Logger.LogInformation("[Sync] Received progress from another device: block {BlockId} at {Timestamp}", blockId, timestamp);
+
         await ScrollToNodeAsync(blockId);
         await InvokeAsync(StateHasChanged);
     }
@@ -148,7 +151,7 @@
     [JSInvokable]
     public async Task HandleTextSelected(string text, string blockId, SelectionCoordinates coords)
     {
-        Console.WriteLine($"[ReaderCanvas] Text selected: {text} at {coords.Top},{coords.Left}");
+        Logger.LogDebug("[ReaderCanvas] Text selected in block {BlockId}", blockId);
         _selectedText = text;
         _selectedBlockId = blockId;
         _selectionCoords = coords;
@@ -172,7 +175,7 @@
     {
         _highlightedBlockId = blockId;
         await InvokeAsync(StateHasChanged);
-        await Task.Delay(3000); // Highlight for 3 seconds
+        await Task.Delay(3000);
         if (_highlightedBlockId == blockId)
         {
             _highlightedBlockId = null;
@@ -192,37 +195,42 @@
     {
         ViewModel = null;
         StatusMessage = "Fetching content...";
-        
+
         var authState = await AuthStateProvider.GetAuthenticationStateAsync();
         var userId = authState.User.FindFirst(System.Security.Claims.ClaimTypes.NameIdentifier)?.Value;
 
-        var result = await Mediator.Send(new GetReaderPageQuery(index, userId));
+        var ebookId = NavigationService.CurrentEbookId;
+        if (ebookId == Guid.Empty)
+        {
+            StatusMessage = "No book selected. Please open a book from your library.";
+            return;
+        }
+
+        var result = await Mediator.Send(new GetReaderPageQuery(ebookId, index, userId));
         if (result.IsSuccess)
         {
             ViewModel = result.Value;
             await NavigationService.UpdateMetadataAsync(ViewModel.CurrentChapterIndex, ViewModel.TotalChapters, ViewModel.ChapterTitle);
-            
-            // Trigger full page graph generation after loading
+
             await Coordinator.ProcessFullPageAsync(GetFullPageContent());
         }
         else
         {
             StatusMessage = $"Error: {result.Errors.FirstOrDefault()?.Message ?? "Failed to load"}";
+            Logger.LogError("Failed to load chapter {Index} for ebook {EbookId}: {Errors}", index, ebookId, string.Join(", ", result.Errors.Select(e => e.Message)));
         }
     }
 
-    private void HandleAiAction(string action)
-    {
-        Console.WriteLine($"Action Triggered from Bubble: {action}");
-    }
-
     public async Task ScrollToNodeAsync(string id)
     {
         try
         {
             await JS.InvokeVoidAsync("eval", $"document.getElementById('{id}')?.scrollIntoView({{ behavior: 'smooth', block: 'center' }});");
-        } 
-        catch { }
+        }
+        catch (Exception ex)
+        {
+            Logger.LogWarning(ex, "Failed to scroll to node {NodeId}.", id);
+        }
     }
 
     private Task HandleUpdate() => InvokeAsync(StateHasChanged);
@@ -231,7 +239,7 @@
     {
         ThemeService.OnThemeChanged -= HandleUpdate;
         NavigationService.OnNavigationChanged -= OnNavigationChanged;
-        
+
         InteractionService.OnScrollToBlockRequested -= HandleScrollRequested;
         InteractionService.OnHighlightBlockRequested -= HandleHighlightRequested;
         InteractionService.OnTextSelected -= HandleTextSelected;