feat: Graph Symmetry Explorer - automorphism detection, orbit computation & symmetry analysis

Interactive tool for exploring graph symmetry structure:
- Backtracking automorphism finder for graphs up to 12 nodes
- Orbit computation via union-find, color-coded visualization
- 8 preset graphs (K5, C6, Petersen, Path, Star, Cube, Prism, Asymmetric Tree)
- Custom adjacency list input
- Animated automorphism stepping with cycle notation
- Vertex/edge transitivity detection
- Proactive insights (structural recommendations, symmetry exploitation hints)
- JSON export of full analysis
- Draggable node layout on Canvas

Author: sauravbhattacharya001

docs/index.html

@@ -53,6 +53,7 @@ <h2>GraphVisual</h2>
         <a href="matching.html" class="sidebar-link"><span class="icon">💍</span>Max Matching</a>
         <a href="graph-advisor.html" class="sidebar-link"><span class="icon">🧠</span>Graph Advisor</a>
         <a href="graph-evolution.html" class="sidebar-link"><span class="icon">🧬</span>Evolution Sim</a>
+        <a href="symmetry.html" class="sidebar-link"><span class="icon">🔮</span>Symmetry Explorer</a>
         <a href="link-predictor.html" class="sidebar-link"><span class="icon">🔮</span>Link Predictor</a>
     </div>
     <div class="sidebar-section">