[FEATURE] [Coinswap] Create Maker RPC Handlers

[hulxv]

Description

Implement all Maker RPC handlers using mill-rpc framework.

Motivation

Port all existing Maker functionality to the new framework with improved error handling and performance.

Proposed Solution

• register_offer
• update_offer
• get_offer
• accept_swap
• get_swap_status
• complete_swap
• abort_swap
• get_balance
• get_statistics

Tasks

• Implement offer management handlers
• Implement swap lifecycle handlers
• Implement wallet handlers
• Implement statistics handlers
• Add proper error handling
• Write unit tests
• Document handler behavior

Expected

• All Maker RPC endpoints functional
• Improved error handling
• Type-safe parameter handling
• Comprehensive test coverage