TI-Sin-Problemas/erpnext_mexico_compliance ? reverse-engineered prompt

Build me an ERPNext app for Mexico compliance that plugs into an existing ERPNext and Frappe setup.

I want it to help businesses follow Mexican tax rules, especially CFDI invoicing. It should add the needed custom fields and reference catalogs for things like tax regime, CFDI use, payment method, payment option, product and service keys, UOM keys, cancellation reasons, CLABE, and tax type. It should also support CFDI stamping for Sales Invoices and Payment Entries, including saving the stamped XML and cancellation acknowledgement, plus handling cancellation with a substitute document when required.

Please make the user experience fit naturally inside ERPNext, with buttons and forms where users would expect them, and validations that clearly tell them what is missing before stamping. Include setup for digital signing certificates and API credentials for the stamping service, with a test mode and a way to check available credits. If you need to, look up current ERPNext and Frappe docs online so the integration feels up to date.