Add support for an MCP (Model Context Protocol) trigger in Rewst,
allowing external AI tools and agents to invoke Rewst workflows
as callable tools via MCP.
As AI platforms like custom GPT agents, local LLMs, and AI
orchestration tools increasingly adopt MCP as a standard, having
a native MCP trigger in Rewst would allow any MCP-compatible AI
tool to trigger workflows directly — without requiring custom
webhooks or API wrappers for each tool.
This would unlock Rewst as an automation backbone for AI-driven
workflows, enabling partners to connect their own AI tooling to
Rewst orchestration without being locked into a specific AI vendor.