Import Betashares Direct Detailed Tax Statement CSV into AMIT statements

Allow Betashares Direct users to upload their EOFY Detailed Tax Statement CSV and use it to pre-fill AMIT statement data for each matching ETF or managed-fund holding. The file contains tax components by symbol and distribution. Navexa should group the data by holding, map the supported components to the relevant AMIT fields, show any unmatched or unsupported items for review, and allow the user to confirm the import. This would remove the current manual process of filtering the CSV, adding values for each holding and entering AMIT components one at a time.