fix: clear portfolio input and dropdown on logout to prevent data leakage

app.py

@@ -3156,6 +3156,9 @@ Please try again with different parameters.
                 # Clear password reset modals
                 gr.update(visible=False),  # password_reset_modal
                 gr.update(visible=False),  # password_update_modal
+                # Clear user input data (SECURITY: prevent data leakage)
+                gr.update(value=""),  # portfolio_input
+                gr.update(choices=[], value=None),  # load_past_portfolio_dropdown
             )
 
         def sync_login(email: str, password: str, current_session: Dict):
@@ -3323,7 +3326,8 @@ Please try again with different parameters.
                 logout_btn, sidebar, results_page, loading_page, history_page,
                 analysis_output, allocation_plot, risk_plot, performance_plot,
                 correlation_plot, optimization_plot, history_table,
-                password_reset_modal, password_update_modal
+                password_reset_modal, password_update_modal,
+                portfolio_input, load_past_portfolio_dropdown
             ]
         )
 
@@ -3351,7 +3355,8 @@ Please try again with different parameters.
                 logout_btn, sidebar, results_page, loading_page, history_page,
                 analysis_output, allocation_plot, risk_plot, performance_plot,
                 correlation_plot, optimization_plot, history_table,
-                password_reset_modal, password_update_modal
+                password_reset_modal, password_update_modal,
+                portfolio_input, load_past_portfolio_dropdown
             ]
         )