* docs: slim CONTRIBUTING.md to the essentials for getting a PR merged
Move dev-environment reference into docs/development.md and the maintainer
release process into docs/releasing.md.
* docs: match CONTRIBUTING visual-proof guidance to the PR template
* docs: cut dev-environment internals and drop the stale release doc
Trim docs/development.md to the setup steps people actually hit, drop
docs/releasing.md in favor of the self-documenting Cut Release workflow,
and move the RC Homebrew cask into the README.
* Document Node compatibility and dev profile cleanup
