refactor: restructure pair programming roles into separate modules}
* Split monolithic pair-implementer role into four specialized modules: - pair-planner: handles planning and task breakdown - pair-implementer: focused on code implementation only - pair-reviewer: handles code review and feedback - pair-reviser: manages revisions based on feedback * Simplify pair-implementer.mjs by removing planning and review logic, reducing file size from 155 to 68 lines of focused implementation code * Update orchestrator.mjs to coordinate new role structure and manage workflow between planning, implementation, review, and revision stages * Enhance MCP integration in src/mcp.mjs to support new role modules * Update bin/architect.js entry point to work with refactored architecture * Revise package.json version bump to reflect structural changes * Update README.md and change-log.md documentation to reflect new modular architecture and role responsibilities