feat(ui/graph): Knowledge Graph Refinement and Sidebar Hierarchy (#25)

This PR addresses several UI/UX and architectural refinements for the Knowledge Graph and Intelligence Sidebar.

### Key Changes:
- **Knowledge Graph (#21, #22)**:
  - Implemented \"pill-shaped\" nodes with dynamic label truncation and SVG tooltips.
  - Added bound-constrained simulation to keep nodes within the viewport.
  - Integrated `ResizeObserver` for dynamic layout handling.
  - Implemented Zoom-to-Fit functionality.
  - Enforced unique concept IDs in AI prompts and hardened JS logic to prevent multi-selection bugs.
- **Intelligence Sidebar (#23)**:
  - Improved visual depth with a radial gradient background for the graph.
  - Increased sidebar divider contrast for better layering.
  - Transformed graph controls into a floating glassmorphism panel.
  - Relocated the \"Logout\" action to the toolbar bottom and rebranded it as \"Exit\".

Fixes #21
Fixes #22
Fixes #23

Reviewed-on: #25
Co-authored-by: Marek Jasiński <jasins.marek@gmail.com>
Co-committed-by: Marek Jasiński <jasins.marek@gmail.com>

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

@@ -79,7 +79,7 @@ public sealed partial class KnowledgeCoordinator : IDisposable
 
     public async Task<KnowledgePacket?> RequestSummaryAndQuizAsync(string content, string tenantId = "global")
     {
-        _quizService.SetHydrating(true);
+        await _quizService.SetHydrating(true);
         LogRequestingSummary(tenantId);
         try
         {
@@ -91,7 +91,7 @@ public sealed partial class KnowledgeCoordinator : IDisposable
                     .Select(q => new QuizQuestionDto(q.Question, q.Options, q.CorrectIndex))
                     .ToList();
                 
-                _quizService.SetQuiz(null, new QuizDto(quizQuestions));
+                await _quizService.SetQuiz(null, new QuizDto(quizQuestions));
                 await _platformService.VibrateSuccessAsync();
                 return packet;
             }
@@ -104,7 +104,7 @@ public sealed partial class KnowledgeCoordinator : IDisposable
         }
         finally
         {
-            _quizService.SetHydrating(false);
+            await _quizService.SetHydrating(false);
         }
         return null;
     }
@@ -112,7 +112,7 @@ public sealed partial class KnowledgeCoordinator : IDisposable
     public async Task ClearAsync()
     {
         await _graphService.Clear();
-        _quizService.SetQuiz(null, null);
+        await _quizService.SetQuiz(null, null);
     }
 
     public void Dispose()