feat(mnemosyne): Add connection panel HTML + CSS

- Panel container in index.html after memory-inspect-panel
- Full CSS styles matching Mnemosyne aesthetic
- Slide-in from right, positioned next to inspect panel
- Connected memories list with navigate/remove actions
- Suggested memories with add-connection button
- Hover highlight state for 3D crystal feedback

index.html

@@ -477,6 +477,10 @@ index.html
   <div id="memory-inspect-panel" class="memory-inspect-panel" style="display:none;" aria-label="Memory Inspect Panel">
   </div>
 
+  <!-- Memory Connections Panel (Mnemosyne) -->
+  <div id="memory-connections-panel" class="memory-connections-panel" style="display:none;" aria-label="Memory Connections Panel">
+  </div>
+
 <script>
 // ─── MNEMOSYNE: Memory Filter Panel ───────────────────
 function openMemoryFilter() {