Fix wealth distribution chart functionality

- Add get_wealth_histogram() method to EconomicModel for histogram data
- Add new API endpoint /simulation/<id>/distribution for chart data
- Extend main data API with include_distribution parameter
- Update real-time progress updates to include distribution data
- Fix frontend updateCharts() to handle wealth distribution chart
- Add distribution data processing in simulation.js
- Update test_charts.py to verify histogram functionality

Resolves issue where wealth distribution chart was not updating during simulations.

test_charts.py

@@ -17,8 +17,8 @@ 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')
+# Get evolution data with distribution
+data_resp = requests.get(f'http://localhost:5000/api/simulation/{sim_id}/data?include_evolution=true&include_distribution=true')
 result = data_resp.json()
 
 print('\nFinal metrics:')
@@ -28,7 +28,40 @@ 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", []))}')
 
+# Test wealth distribution
+if 'distribution' in result:
+    dist_data = result['distribution']
+    print(f'\nWealth Distribution:')
+    print(f'  Bins: {dist_data.get("bins", 0)}')
+    print(f'  Labels: {len(dist_data.get("labels", []))}')
+    print(f'  Counts: {len(dist_data.get("counts", []))}')
+    
+    if dist_data.get('labels') and dist_data.get('counts'):
+        print('\n  Distribution Histogram:')
+        for label, count in zip(dist_data['labels'], dist_data['counts']):
+            bar = '█' * max(1, count // 2)  # Visual bar representation
+            print(f'    {label:<20} {count:>3} agents {bar}')
+        print('\n✅ Wealth distribution chart should now work!')
+    else:
+        print('\n❌ No distribution data available')
+else:
+    print('\n❌ No distribution data in response')
+
+# Test dedicated distribution endpoint
+print('\nTesting dedicated distribution endpoint...')
+dist_resp = requests.get(f'http://localhost:5000/api/simulation/{sim_id}/distribution?bins=8')
+if dist_resp.status_code == 200:
+    dist_result = dist_resp.json()
+    hist_data = dist_result.get('histogram', {})
+    print(f'  Total agents: {hist_data.get("total_agents", 0)}')
+    print(f'  Bins: {hist_data.get("bins", 0)}')
+    print(f'  Labels count: {len(hist_data.get("labels", []))}')
+    print(f'  Counts sum: {sum(hist_data.get("counts", []))}')
+    print('\n✅ Distribution endpoint working!')
+else:
+    print(f'\n❌ Distribution endpoint failed: {dist_resp.status_code}')
+
 if len(result["evolution"]["gini_coefficients"]) > 0:
-    print('\n✅ Charts should now be populated with data!')
+    print('\n🎯 All charts should now be populated with data!')
 else:
     print('\n❌ No data available for charts')