Start Phase 2 with durable history and hierarchy commands

[WebCrew]

Summary

• mark Phase 1 complete and activate Phase 2 — Editor Foundation
• add deep node and subtree duplication with fresh IDs
• add safe editor reparenting to another node or Scene Root
• render nested hierarchy depth and prevent invalid descendant targets
• include duplication and reparenting in Undo/Redo
• persist bounded, validated Scene History inside .parlyn
• restore Undo/Redo after project close and full application restart only when history matches the loaded Scene
• ignore stale, oversized or invalid history without blocking project loading
• fix subtree deletion so no descendant viewport objects remain
• publish the tested result as distinctly named Beta 5

Local verification

• npm run check
• npm run build:renderer:release
• git diff --check

Closes #29
Closes #30