Critical fixes (review findings #1, #2, #3):
- Create IEbookRepository abstraction in Application layer
- Remove illegal EF Core dependency from IngestEbookCommandHandler
- Create EbookRepository implementation in Infrastructure/Persistence
- Create ISyncBroadcaster in Application/Abstractions/Messaging
- Create SignalRSyncBroadcaster in Infrastructure/RealTime
- Move UpdateReadingProgressCommandHandler from Infrastructure → Application
- Add EbookId to GetReaderPageQuery and IEpubReader signature
- Rewrite EpubReaderService: DB-resolved file path, remove auto-provisioning
- Split EpubService.cs into EpubReaderService.cs + EpubMetadataExtractor.cs
- Add CurrentEbookId to IReaderNavigationService and ReaderNavigationService
- Update WasmEpubReader and /api/epub endpoint for new signature

High severity fixes (#4, #6, #7, #8, #16):
- Change BookStorageService registration from Singleton → Scoped
- Fix empty catch{} in ReaderCanvas JS interop init — now logs warnings
- Replace all Console.WriteLine with ILogger in KnowledgeService + ReaderCanvas
- Cache JsonSerializerOptions as static field in KnowledgeService
- Wrap SyncService Task.Run body in comprehensive try/catch with ILogger

Medium/Low fixes (#11, #13, #14, #15, #18, #20):
- BookIngestionModal.DisposeAsync now nullifies _epubBytes (50MB array)
- KnowledgeCoordinator.OnGraphUpdated: Action<T> → Func<T, Task>
- BookStorageService: Path.Combine → forward-slash string interpolation
- SignalR CancellationToken passed as named parameter (not payload arg)

@@ -43,0 +45,4 @@
+    /// Gets or sets a value indicating whether the ebook has been processed by the AI ingestion engine
+    /// and is ready for reading (Knowledge Units generated).
+    /// </summary>
+    public bool IsReadyForReading { get; set; } = false;

@@ -48,1 +50,3 @@
-builder.Services.AddSingleton<IBookStorageService>(new ThrowingBookStorageService());
+builder.Services.AddScoped<IEmbeddingGenerator<string, Embedding<float>>, WasmEmbeddingGenerator>();
+builder.Services.AddScoped<IBookStorageService, WasmBookStorageService>();
+builder.Services.AddScoped<IEbookRepository, WasmEbookRepository>();

@@ -0,0 +42,4 @@
+    private readonly List<Author> _stagedAuthors = new();
+    private readonly List<Ebook> _stagedEbooks = new();
+
+    public async Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)

@@ -0,0 +12,4 @@
+        _httpClient = httpClient;
+    }
+
+    public async Task BroadcastProgressAsync(

@@ -296,0 +318,4 @@
+    return Results.Ok();
+});
+
+repoApi.MapPost("/ebook/add", (Ebook ebook, IEbookRepository repo) =>