v0.7.3

Changed

• The command guide and the shipped API header now say that every command except
  env, built-in or discovered, is served as an MCP tool when dotagents starts with
  DOTAGENTS_MCP=stdio, and that AGENT_HELP=1 turns --help into a JSON document.
  The authoring guide asks overlays to ship command modules rather than loose
  scripts, and skills to name the tools they use.

Full Changelog: v0.7.2...v0.7.3