Fix export logic in app.py: update the export base to concatenate the current portfolio instead of the export file, ensuring accurate data representation when adding to the export.

app.py

@@ -1105,13 +1105,12 @@ with tab2:
                     st.download_button(label="Download Portfolio", data=st.session_state['export_file'].to_csv(index=False), file_name="portfolio.csv", mime="text/csv")
                 with merge_port:
                     if st.button("Add to export"):
-                        st.session_state['export_base'] = pd.concat([st.session_state['export_base'], st.session_state['export_file']])
+                        st.session_state['export_base'] = pd.concat([st.session_state['export_base'], st.session_state['portfolio']])
             else:
                 st.error("No portfolio to download")
             
             display_frame_source = st.selectbox("Display:", options=['Portfolio', 'Export Base'], key='display_frame_source')
             if display_frame_source == 'Portfolio':
-                # Add pagination controls below the dataframe
                 total_rows = len(st.session_state['portfolio'])
                 rows_per_page = 500
                 total_pages = (total_rows + rows_per_page - 1) // rows_per_page  # Ceiling division