refactor(app-control): move the control-skill contract to plugin level with feature folders and grouped ids #9579

Slice A1 of #9507, from poteto's draft (comment) amended to the owner's decisions.

Problem

Two contracts describe one thing: app-control's drive/reference/control-skill.md and testing's reference/feature-map.md define different feature sections.

Fix

• git mv plugins/app-control/skills/drive/reference/control-skill.md plugins/app-control/reference/control-skill.md and repoint every consumer (drive/SKILL.md, plugins/app-control/README.md, docs/upstream/cursor-pstack.md).
• Feature files become features/[<module>/]<feature>/README.md with H2 sections Parts, Sub-features, Entry points, Reset, Drive, Gotchas (#7581 Parts ruling). ## States goes. Every entry point ends driven or not driven: <reason>.
• Index line: - <title> | features/<module>/<feature>/README.md | entry points: <n> | sources: <glob>[, <glob>].
• A legacy features/<f>.md still resolves. Keep the "Writing the Capture section" block whole.
• Drive's feature resolution ships in the same PR: features/<id>/README.md, then features/<id>.md, with <id> = <feature> or <module>/<feature>.
• Evals grouped-feature-id-resolves and flat-legacy-feature-id-resolves. Fragment: app-control minor.

Done when

• test -f plugins/app-control/reference/control-skill.md && test ! -e plugins/app-control/skills/drive/reference/control-skill.md exits 0.
• rg -n 'skills/drive/reference/control-skill' plugins docs --glob '!**/CHANGELOG.md' prints nothing.
• No ## States row in the contract; exactly six section rows (Parts, Sub-features, Entry points, Reset, Drive, Gotchas).
• Drive's after evals are non-inferior to the before baseline.
• python3 scripts/check-line-citations.py exits 0.

Blocked by: none.