Adds onboarding decision tree to getting-started/README.md so users can
quickly identify the right setup command for their situation.
Adds hardware vision overview to hardware/README.md explaining the
Peripheral trait and supported board types.
Expands project/README.md with scope explanation describing the purpose
of project snapshots and how they relate to documentation maintenance.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
