Charlymd/module-dolibarr-lemonfacturx ? reverse-engineered prompt

Build me a Dolibarr module that automatically turns customer invoices into Factur X EN16931 PDF A 3 files with the XML embedded inside.

I want it to hook into invoice PDF generation, keep the normal PDF if something is not compatible, and clearly warn me when required data is missing, like seller and buyer identifiers, bank details, VAT settings, or a valid embedded font for PDF A.

Please add a configuration page where I can set the default payment method, bank info, legal mentions, error handling mode, and choose the PDF font. I also want a simple diagnosis area that shows if everything is ready.

On the invoice page, add actions to check the generated Factur X file and to regenerate it when needed. If it helps, look up the current Dolibarr and Factur X docs online so the implementation follows the right rules and validation checks.