0.30.0

Added

• The ESS agent plugin lives in this repository. plugins/ess/ carries the skills ess (front
  door), specify, coverage and retrofit, and the Claude agents author, retrofitter and
  conformance. .claude-plugin/marketplace.json and .agents/plugins/marketplace.json serve it
  as ess@ess for Claude Code and Codex. specify and coverage move from the ess-specify
  plugin in beyond10x/agentplugins.
• ess skill [<path>] prints the skills and agents embedded in the binary: the front door and an
  index with no path, one file with a path, the index as JSON with --json. An unknown path exits
  2 and lists the valid ones. ess --help lists skill after the four areas.
• cargo xtask plugin check, run by cargo xtask release verify, refuses a plugin manifest whose
  version differs from the workspace, a marketplace under another identity, a skill named unlike
  its folder, and an agent wrapper that names no existing skill.