feat(ui/graph): optimize graph dynamics, immersive reader, and code blocks

- Fix #16: Implement D3.js transitions and active state badges for Knowledge Graph.
- Fix #12: Implement Immersive Reader Layout with Merriweather typography.
- Fix #20: Professional code block styling with high contrast and monospace fonts.
- Resolve DI runtime error in WASM by adding dummy services.
- Replace generic 'Not Found' message with Nexus preloader.
- Enforce 'no async void' architecture across UI services.

src/NexusReader.Web.Client/Program.cs

@@ -4,6 +4,9 @@ using NexusReader.Application.Abstractions.Services;
 using NexusReader.Web.Client.Services;
 using NexusReader.UI.Shared.Services;
 using NexusReader.Application;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.AI;
+using NexusReader.Data.Persistence;
 
 
 var builder = WebAssemblyHostBuilder.CreateDefault(args);
@@ -32,7 +35,24 @@ builder.Services.AddCascadingAuthenticationState();
 builder.Services.AddScoped<IKnowledgeService, WasmKnowledgeService>();
 builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
 
+// Dummy registrations for server-only handlers to satisfy DI validation
+builder.Services.AddSingleton<IDbContextFactory<AppDbContext>>(new ThrowingDbContextFactory());
+builder.Services.AddSingleton<IEmbeddingGenerator<string, Embedding<float>>>(new ThrowingEmbeddingGenerator());
+
 builder.Services.AddApplication();
 builder.Services.AddScoped<IEpubService, WasmEpubService>();
 
 await builder.Build().RunAsync();
+
+public class ThrowingDbContextFactory : IDbContextFactory<AppDbContext>
+{
+    public AppDbContext CreateDbContext() => throw new NotSupportedException("DbContext cannot be used in WASM client.");
+}
+
+public class ThrowingEmbeddingGenerator : IEmbeddingGenerator<string, Embedding<float>>
+{
+    public void Dispose() { }
+    public Task<GeneratedEmbeddings<Embedding<float>>> GenerateAsync(IEnumerable<string> values, EmbeddingGenerationOptions? options = null, CancellationToken cancellationToken = default) 
+        => throw new NotSupportedException("Embedding generation cannot be used in WASM client.");
+    public object? GetService(Type serviceType, object? serviceKey = null) => null;
+}