Move the following completed changes from openspec/changes/ to
openspec/changes/archive/2026-06-12-completed-changes-archive/:
- multi-session-terminal-ux
- reorganize-long-files
- working-copies
- workspace-first-ui
Update parent and archive .pi-map*.md indexes to reflect the move and
remove the transient active-changes-archive grouping.
openspec/changes/ now contains only the archive/ directory.
Developer