Add a new provider module for LAVA Business (api.lava.ru):
- invoice creation via POST /business/invoice/create signed with
HMAC-SHA256 over the raw request body in the Signature header
- webhook handling with Authorization-header signature verification
that accepts both raw-body and sorted-keys JSON canonicalizations
(legacy PHP SDK shops sign the latter), plus amount cross-check
before finalizing a successful payment
- pending invoice reuse through /business/invoice/status
- Telegram pay_lava callback flow and Web App payment creation
- admin settings manifest fields, presentation overrides, and
RUB-only currency support declared on the provider SPEC
Register the SPEC in the provider registry and wire the provider into
the payment method order, success-email labels, and locale override
prefixes.
3252a8