Rename Engineer in Box to Shiny (gt-8tmz.10)

Renamed mol-engineer-in-box to mol-shiny across all documentation
and test code. This is a Mad Max reference - the canonical 'right
way to engineer'.

Files updated:
- docs/architecture.md (15 references)
- docs/molecules.md (7 references)
- docs/bootstrap.md (1 reference)
- docs/molecular-chemistry.md (1 reference)
- docs/polecat-wisp-architecture.md (1 reference)
- internal/beads/molecule_test.go (test function rename)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/bootstrap.md

@@ -221,4 +221,4 @@ echo "Bootstrap complete!"
 After bootstrapping:
 1. Start a Mayor session: `gt mayor attach`
 2. Check for work: `bd ready`
-3. Spawn workers with molecules: `gt spawn --issue <id> --molecule mol-engineer-in-box`
+3. Spawn workers with molecules: `gt spawn --issue <id> --molecule mol-shiny`