Update Paycrest protocol architecture on the documentation

[SarahSync]

Description
The official technical documentation for the Paycrest protocol is currently outdated. We need to update the architectural diagrams and written guides to reflect the current system design, service interactions, and data flows.

Scope of Updates

• System Overview: Revise the architecture diagram showing the relationship between the Payment order, Gateway escrow, Aggregator nodes, and Provision Node and recipients
• Component Responsibilities: Define the updated roles and written guides within the current protocol version.

Updated Image