feat(ui/arch): Optimize Graph Dynamics, Immersive Reader, and Core Stability (#19)

This PR introduces a major optimization of graph dynamics, immersive reading experience, and architectural stabilization.

### 🚀 Key Improvements

- **Knowledge Graph (Fix #16)**:
  - Implemented smooth D3.js transitions using the General Update Pattern.
  - Added "Neon Flash" entry animations and dynamic node dimming for better focus.
- **Immersive Reader (Fix #12)**:
  - Standardized centered layout (`max-width: 800px`) with **Merriweather** typography.
  - Optimized line-height and letter-spacing for premium readability.
- **Technical Code Blocks (Fix #20)**:
  - High-contrast dark containers for code snippets.
  - **JetBrains Mono** integration and neon-accented scrollbars.
- **Architectural Stabilization**:
  - Enforced a strict **'no async void'** policy in UI services using `Func<Task>`.
  - Resolved WASM runtime DI errors by implementing dummy service proxies for server-side dependencies.
  - Replaced generic 'Not Found' message with a branded Nexus preloader.

Fixes #7, Fixes #12, Fixes #16, Fixes #20.

Reviewed-on: #19
Co-authored-by: Marek Jasiński <jasins.marek@gmail.com>
Co-committed-by: Marek Jasiński <jasins.marek@gmail.com>

src/NexusReader.UI.Shared/Services/KnowledgeGraphService.cs

@@ -8,36 +8,36 @@ public sealed class KnowledgeGraphService : IKnowledgeGraphService
     public string? ActiveNodeId { get; private set; }
     public bool IsLoading { get; private set; }
 
-    public event Action? OnGraphUpdated;
-    public event Action<string>? OnActiveNodeChanged;
-    public event Action<bool>? OnLoadingChanged;
+    public event Func<Task>? OnGraphUpdated;
+    public event Func<string, Task>? OnActiveNodeChanged;
+    public event Func<bool, Task>? OnLoadingChanged;
 
-    public void UpdateGraph(GraphDataDto newData)
+    public async Task UpdateGraph(GraphDataDto newData)
     {
         CurrentGraphData = newData;
         IsLoading = false;
-        OnLoadingChanged?.Invoke(false);
-        OnGraphUpdated?.Invoke();
+        if (OnLoadingChanged != null) await OnLoadingChanged(false);
+        if (OnGraphUpdated != null) await OnGraphUpdated();
     }
 
-    public void SetActiveNode(string nodeId)
+    public async Task SetActiveNode(string nodeId)
     {
         if (ActiveNodeId == nodeId) return;
         ActiveNodeId = nodeId;
-        OnActiveNodeChanged?.Invoke(nodeId);
+        if (OnActiveNodeChanged != null) await OnActiveNodeChanged(nodeId);
     }
 
-    public void SetLoading(bool isLoading)
+    public async Task SetLoading(bool isLoading)
     {
         IsLoading = isLoading;
-        OnLoadingChanged?.Invoke(isLoading);
+        if (OnLoadingChanged != null) await OnLoadingChanged(isLoading);
     }
 
-    public void Clear()
+    public async Task Clear()
     {
         CurrentGraphData = null;
         ActiveNodeId = null;
         IsLoading = false;
-        OnGraphUpdated?.Invoke();
+        if (OnGraphUpdated != null) await OnGraphUpdated();
     }
 }