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.

app/models/economic_model.py

@@ -262,6 +262,23 @@ class EconomicSimulation:
         
         return iterations, total_wealth, gini_coefficients
     
+    def get_inequality_evolution(self) -> Tuple[List[int], List[float], List[float], List[float]]:
+        """
+        Get inequality evolution data for plotting.
+        
+        Returns:
+            Tuple of (iterations, gini_over_time, top10_share_over_time, capital_share_over_time)
+        """
+        if not self.snapshots:
+            return [], [], [], []
+        
+        iterations = [s.iteration for s in self.snapshots]
+        gini_coefficients = [s.gini_coefficient for s in self.snapshots]
+        top10_shares = [s.wealth_concentration_top10 for s in self.snapshots]
+        capital_shares = [s.capital_share for s in self.snapshots]
+        
+        return iterations, gini_coefficients, top10_shares, capital_shares
+    
     def get_agent_wealth_distribution(self) -> Dict[str, List[float]]:
         """
         Get current wealth distribution across all agents.