Use whenever the user is customizing, overriding, or debugging PDF output in Perfex CRM — invoice PDFs, estimate PDFs, proposal PDFs, payment receipts, contract PDFs, statement PDFs, credit note PDFs, the `my_` prefix override convention, TCPDF library usage, `App_items_table` customization, font configuration (freesans, dejavusans, droidsansfallback), PDF merge fields, logo/heading settings, or e-invoice JSON/XML export (3.4.0+).
