Fix summary not displaying: frontend was looking for result.final_answer but backend returns result.summary

CRITICAL BUG FIX - Summary Display:

ISSUE:
- Frontend showed 'Analysis complete. Check the generated artifacts.' instead of actual summary
- User saw generic message instead of detailed analysis results

ROOT CAUSE:
- Frontend ChatInterface.tsx line 193: result.final_answer
- Backend orchestrator.py line 2438: result['summary']
- Field name mismatch!

BACKEND RETURNS (orchestrator.py lines 2437-2450):
{
'status': 'success',
'summary': summary_text, # Backend uses 'summary'
'metrics': metrics_data,
'artifacts': artifacts_data,
'plots': plots_data,
'workflow_history': workflow_history
}

FRONTEND WAS CHECKING:
result.final_answer || 'Analysis complete...' # Wrong field name!

FIX:
Changed frontend to check result.summary first:
const summaryText = result.summary || result.final_answer || 'Analysis complete...';

Now supports both field names for backward compatibility.

EVIDENCE FROM LOGS:
- Backend log: ' Enhanced summary generated with 3 plots, 2 metrics'
- Backend log: ' Session saved: 12a697fa-9520-451e-bf0e-8de78a01c9dd'
- Summary WAS generated but not displayed due to field mismatch

USER WILL NOW SEE:
- Full analysis summary with insights, findings, recommendations
- Model performance metrics
- Key insights from data
- Next steps and recommendations
Instead of just 'Analysis complete. Check the generated artifacts.'

FRRONTEEEND/components/ChatInterface.tsx

@@ -186,7 +186,9 @@ export const ChatInterface: React.FC<{ onBack: () => void }> = ({ onBack }) => {
       assistantContent += `📈 **Generated ${plots.length} Visualizations**\n\n`;
     }
     
-    assistantContent += result.final_answer || 'Analysis complete. Check the generated artifacts.';
+    // Extract summary from backend (field changed from final_answer to summary)
+    const summaryText = result.summary || result.final_answer || 'Analysis complete. Check the generated artifacts.';
+    assistantContent += summaryText;
     
     // Add assistant message with result
     const assistantMessage: Message = {