Epic: Design and documentation debt #454

Spec: architecture index
Plan: architecture-doc-refresh.md

Rules that live only in the plan that produced them are rules the next reader re-litigates. Four decisions
have no architecture document at all: the home-resolution ladder, root ownership (the caller owns, the
leaf receives), machine-wide install locations, and the scenario tier.

Also the closure pass over the phase-8 ledger, where four steps record their own completion inside notes
that still read as open, and the user-facing guides that do not yet exist.