[aroff]

Summary

Adds fastskill managed enroll | apply | status | unenroll on top of the signed managed state format from #415 (ADR-0016 decisions 8–12 and 17).

• apply verifies the newest signed state, stages the listed skills into a private store, and deploys each one into every agent's user skills folder (the targets come from aikit's per-user skills folders), as a symlink or a verified copy. It records which entries it owns.
  • Identical existing entries are adopted.
  • Foreign content is reported as a collision and left alone.
  • Owned entries that are no longer listed are removed.
  • Blocked or disallowed content, and changed owned copies, go to a quarantine instead of being deleted.
  • Project-level id clashes are reported.
• An expired state changes nothing except the quarantine.
• When the source is unreachable, the last accepted state is used.
• One apply runs per user at a time. A busy apply exits quietly without a terminal and explains itself in one.
• enroll records the source and a machine id. When the system settings name the source, the first apply enrolls.
• status is read-only. --report adds the last apply's full report.
• unenroll removes what managed state placed and keeps the quarantine. It's refused when the system file sets required = true.
• managed enroll, managed apply and managed unenroll are classified as write operations; managed status is read-only.
• Bumps aikit to 9de6b40 and cli-framework to 971134fd. CaseRunOptions.capture_harness is set to false.
• Docs: webdocs/cli-reference/managed-command.mdx.

Test plan

• cargo clippy --workspace --all-features --all-targets -- -D warnings
• cargo fmt --all --check
• cargo nextest run --workspace --all-features -E 'not test(install_e2e_tests)'
• Coverage gate passes (≥ 90%) on every modified production file
• Unit tests for the engine and the command, plus a binary test against an isolated HOME and XDG folders