Mermail agent skill (Claude Skills

Mermail agent skill (Claude Skills + MCP): the live Mermail MCP server exposed 83 tools, but the project's own coverage file knew 74, so their validation failed on main. I built a skill for the nine uncovered webhook tools, with the contract taken from the live catalog (confirmation token bound to the exact arguments, delivery is asynchronous, test payloads are synthetic), and a recorded live run where their check goes from exit 1 to green. Public PR: github.com/Nudgen-Marketing/mermail-skills/pull/370