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/Components/Organisms/KnowledgeGraph.razor

@@ -46,7 +46,7 @@
         GraphService.OnLoadingChanged += HandleLoadingChange;
     }
 
-    private async void HandleGraphUpdate()
+    private async Task HandleGraphUpdate()
     {
         if (_module == null) return;
         
@@ -62,13 +62,13 @@
         await InvokeAsync(StateHasChanged);
     }
 
-    private async void HandleActiveNodeChange(string nodeId)
+    private async Task HandleActiveNodeChange(string nodeId)
     {
         if (_module == null) return;
         await _module.InvokeVoidAsync("setActiveNode", nodeId);
     }
 
-    private async void HandleLoadingChange(bool isLoading)
+    private async Task HandleLoadingChange(bool isLoading)
     {
         await InvokeAsync(StateHasChanged);
     }
@@ -81,7 +81,7 @@
             
             if (GraphService.CurrentGraphData != null)
             {
-                HandleGraphUpdate();
+                await HandleGraphUpdate();
             }
         }
     }
@@ -100,7 +100,7 @@
     [JSInvokable]
     public async Task OnNodeClicked(string nodeId)
     {
-        InteractionService.NotifyNodeSelected(nodeId);
+        await InteractionService.NotifyNodeSelected(nodeId);
         
         if (OnNodeSelected.HasDelegate)
         {
@@ -109,7 +109,7 @@
     }
 
 
-    private async void HandleFocusSimulation()
+    private async Task HandleFocusSimulation()
     {
         if (_module == null) return;
         try