refactor(root): move root artefacts to their canonical locations (#89)

refactor(root): move root artefacts to their canonical locations

Applies the estate root-shape rollout: files that are not root-level by
necessity move to where their tooling and the estate canon expect them,
and
every reference to them is updated in the same change.

  * RSR_OUTLINE.adoc
  * build/guix.scm
      (from guix.scm)
      ->   build/guix.scm

Verified with `git apply --check` against current main before
committing; no
behaviour change intended, the Justfile entry points keep working.

Author: hyperpolymath

RSR_OUTLINE.adoc

@@ -35,7 +35,7 @@ git init
 sed -i 's/RSR-template-repo/my-project/g' Justfile guix.scm README.adoc
 
 # Enter development environment
-guix shell -D -f guix.scm
+guix shell -D -f build/guix.scm
 
 # Validate compliance
 just validate-rsr