fix: #874

- Implement Nostr event stream visualization
- Add js/nostr-event-visualizer.js with particle visualization
- Add docs/nostr-event-visualizer.md with documentation
- Add script to index.html

Addresses issue #874: [NEXUS] Implement Nostr Event Stream Visualization

Features:
1. Connect to Nostr relay via WebSocket
2. Subscribe to event stream
3. Visualize events as colored particles
4. Color-coded by event type (text_note, recommend_server, etc.)
5. Animated particle system with turbulence
6. Reconnect on disconnect

Event types visualized:
- text_note: Blue particles
- recommend_server: Gold particles
- contact_list: Cyan particles
- encrypted_direct_message: Pink particles

Components:
- NostrEventVisualizer: Main visualization class
- Particle system: Three.js points
- Color manager: Event type colors
- Animation engine: Particle movement and pulsing

index.html

@@ -395,6 +395,7 @@
 <div id="memory-connections-panel" class="memory-connections-panel" style="display:none;" aria-label="Memory Connections Panel"></div>
 
 <script src="./boot.js"></script>
+<script src="./js/nostr-event-visualizer.js"></script>
 <script src="./avatar-customization.js"></script>
 <script src="./lod-system.js"></script>
 <script>