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/ReaderInteractionService.cs

@@ -2,28 +2,28 @@ namespace NexusReader.UI.Shared.Services;
 
 public sealed class ReaderInteractionService : IReaderInteractionService
 {
-    public event Action<string>? OnNodeSelected;
-    public event Action<string>? OnScrollToBlockRequested;
-    public event Action<string>? OnHighlightBlockRequested;
-    public event Action<string, string, SelectionCoordinates>? OnTextSelected;
+    public event Func<string, Task>? OnNodeSelected;
+    public event Func<string, Task>? OnScrollToBlockRequested;
+    public event Func<string, Task>? OnHighlightBlockRequested;
+    public event Func<string, string, SelectionCoordinates, Task>? OnTextSelected;
 
-    public void NotifyNodeSelected(string nodeId)
+    public async Task NotifyNodeSelected(string nodeId)
     {
-        OnNodeSelected?.Invoke(nodeId);
+        if (OnNodeSelected != null) await OnNodeSelected(nodeId);
     }
 
-    public void RequestScrollToBlock(string blockId)
+    public async Task RequestScrollToBlock(string blockId)
     {
-        OnScrollToBlockRequested?.Invoke(blockId);
+        if (OnScrollToBlockRequested != null) await OnScrollToBlockRequested(blockId);
     }
 
-    public void RequestHighlightBlock(string blockId)
+    public async Task RequestHighlightBlock(string blockId)
     {
-        OnHighlightBlockRequested?.Invoke(blockId);
+        if (OnHighlightBlockRequested != null) await OnHighlightBlockRequested(blockId);
     }
 
-    public void NotifyTextSelected(string text, string blockId, SelectionCoordinates coords)
+    public async Task NotifyTextSelected(string text, string blockId, SelectionCoordinates coords)
     {
-        OnTextSelected?.Invoke(text, blockId, coords);
+        if (OnTextSelected != null) await OnTextSelected(text, blockId, coords);
     }
 }