Add Financewolf to Document Validation users

[radnams]

Adds Financewolf to the Users list under Document Validation, in the same shape as the two existing entries.

Financewolf is a production validation service built on phive and phive-rules. For the record:

• Self-hosted Java validator service (Financewolf validator 1.2.0), in production since September 2026
• phive 12.1.0, phive-rules 4.5.6 (Peppol rules 4.5.6, OpenPeppol 2026.5 / BIS Billing 3.0.21), Saxon 12.10
• Validates UBL Invoice and CreditNote documents against EN 16931 and Peppol BIS Billing 3; the XML, XSD, EN 16931 and Peppol layers are reported separately
• Every result names the immutable ruleset it ran against, and the public rulesets endpoint lists the releases and the observed engine versions: https://api.ironfang.uk/financewolf/v1/einvoices/rulesets
• Free anonymous validation at https://ironfang.uk/tools/peppol-validator, and a REST API for saved results and signed reports (OpenAPI: https://api.ironfang.uk/financewolf/openapi.yaml)

I run Ironfang, which builds Financewolf. Happy to adjust the wording or drop the entry if it does not fit the list.