v0.8.1

Added

• Overlay commands get a launcher on PATH: each top-level bin/<name>.py, and
  each [scripts] entry in overlay.toml (name = "path" adds or replaces one,
  name = false opts a bin/<name>.py out). The launchers live in the agents'
  venv, in <venv>/overlays/: <name>.exe on Windows, made with distlib's
  ScriptMaker so no command interpreter parses the arguments, and a /bin/sh
  script elsewhere. They run the script through $<NAME>_OVERLAY_ROOT when they
  run, so only a new interpreter needs them made again. init and overlays add /
  sync / remove keep them current and delete those no overlay has; two
  overlays with one script name is an error naming both.
• dotagents env puts the launcher directory of the venv AGENTS_PYTHON names
  first on PATH, ahead of the levels' bin dirs, and takes any other venv's
  off it.
• A project gets its own venv when one of its overlays has scripts.
• New dependency: distlib>=0.4.0,<0.5, vendored in the .pyz.

Full Changelog: v0.8.0...v0.8.1