* fix(setup): clarify terminal installation and report progress

Report missing setup tools together, preserve JSON updater interfaces, and explain CLI helper failures without losing the installed widget. Exercise the documented multiline bootstrap with terminal prompts.

Documentation: update README, Development and Unreleased. Existing usage guidance and translations remain accurate; TODO parity entries are unaffected.

* fix(setup): check dependencies before platform and user guards

Avoid checkout path resolution in standalone setup and report missing uname/id before invoking them. Preserve explicit updater metadata arguments, including empty paths.

Documentation: reconcile Development and the Unreleased entry. Extend isolated setup coverage for stripped PATH and installation without dirname; parity TODO remains unaffected. Addresses PR #540 review feedback.