API parity

The binding parity map tracks the Diplomat bridge by capability and links to its regression tests. The handwritten C symbol matrix has been replaced by that map.

Use the C API header or C++ headers for exact signatures. Python's public API is checked against its method inventory.

Local ZATCA validation is exposed as fatoora_xml_validate_zatca in C and validate_zatca_invoice_from_str in Python. Both preserve reports for rejection or incomplete coverage and structured errors for execution failure.