updateself v2.1.0

updateself 2.1.0

This release adds explicit self-management commands:

updateself --check-self-update
updateself --self-update --dry-run
updateself --self-update
updateself --uninstall --dry-run
updateself --uninstall

Self-update and uninstall request confirmation by default. Use --yes only after
reviewing the plan. Normal system/tool update runs do not replace updateself.

Git/archive and macOS package installations download the latest stable release,
verify SHA256SUMS, and verify provenance when GitHub CLI is available. Install
locations are preserved. Git/archive installation failures restore previous
managed files. macOS installers use the native Installer transaction; no automatic
rollback is promised. Modified Git/macOS files are retained during uninstall.

Other native packages use their owning manager and its configured repositories.
No external registry submissions or repository configuration are added. Until an
updateself repository/channel is available, install matching GitHub release
packages manually. Declarative Nix installs must be edited in their configuration;
modern imperative profile detection requires Python 3.

The macOS installers remain unsigned and not notarized. HTTPS checksums provide
release integrity; they are not platform code signing. See the Wiki Self-Management
guide for supported owners, dependencies, recovery and limitations.

GPL-3.0-only.