Fix Markov simulation chart display issue

- Fix circular import issue by moving simulation_manager to app/__init__.py
- Enhance get_wealth_evolution to include inequality metrics data
- Add get_inequality_evolution method for complete chart data
- Update API to return top10_shares and capital_shares in evolution data
- Modify onSimulationComplete to fetch and populate charts with complete data
- Fix simulation threading to properly mark completion state
- Add test script to verify chart data generation

The charts now properly display simulation results by fetching complete
evolution data when simulation completes, resolving the empty diagrams issue.

test_charts.py

@@ -0,0 +1,34 @@
+import requests
+import json
+import time
+
+# Test simulation workflow
+data = {'r_rate': 0.05, 'g_rate': 0.03, 'num_agents': 50, 'iterations': 200}
+
+# Create simulation
+create_resp = requests.post('http://localhost:5000/api/simulation', json=data)
+sim_id = create_resp.json()['simulation_id']
+print('Created simulation:', sim_id)
+
+# Start simulation
+start_resp = requests.post(f'http://localhost:5000/api/simulation/{sim_id}/start')
+print('Started simulation:', start_resp.json()['status'])
+
+# Wait for completion
+time.sleep(3)
+
+# Get evolution data
+data_resp = requests.get(f'http://localhost:5000/api/simulation/{sim_id}/data?include_evolution=true')
+result = data_resp.json()
+
+print('\nFinal metrics:')
+print(f'  Iterations: {len(result["evolution"]["iterations"])}')
+print(f'  Final Gini: {result["evolution"]["gini_coefficients"][-1]:.3f}')
+print(f'  Final Total Wealth: ${result["evolution"]["total_wealth"][-1]:.2f}')
+print(f'  Top 10% data points: {len(result["evolution"].get("top10_shares", []))}')
+print(f'  Capital share data points: {len(result["evolution"].get("capital_shares", []))}')
+
+if len(result["evolution"]["gini_coefficients"]) > 0:
+    print('\n✅ Charts should now be populated with data!')
+else:
+    print('\n❌ No data available for charts')