Add 2328.io payment gateway

[Const-NW]

This issue

remnashop_add_pay2328_gateway_commit.patch

adds support for 2328.io as a payment gateway.

Included changes:

• Add PAY_2328 payment gateway type.
• Add gateway settings DTO with project_uuid, api_key, and ttl_seconds.
• Add Pay2328Gateway.
• Register the gateway in DI and Retort mappings.
• Add database migration to insert an inactive PAY_2328 gateway row with default settings.
• Add webhook handling with signature verification.
• Map 2328 payment statuses to Remnashop transaction statuses.
• Add Russian label for the gateway.

Implementation notes:

• 2328 create-payment requests are signed with HMAC-SHA256 using the configured API key.
• Webhook callbacks are verified before transaction processing.
• paid and overpaid are treated as successful statuses.
• Pending and failed/canceled statuses are handled without marking the payment as completed.
• The gateway uses per-payment callback URLs, so it does not require static webhook registration.

This PR does not include deployment-specific configuration, domains, API keys, or local project settings.