9ca2c8ab87
These four cycles' specs and plans (glossary integration + skill,
milestone-close gate, specify entry path) were self-development
artefacts committed before specs/plans became gitignored working files
(08bc2aa). They are all long shipped and nothing references them.
Remove them from HEAD to match the new convention — git history retains
them, and docs/specs/ + docs/plans/ are now globally gitignored.