Make cleanup-eligible worktree review/apply flow symmetric

[chubes4]

Problem

The current worktree cleanup UX exposes a safe-looking review surface for explicit cleanup_eligible worktrees, but does not provide an obvious symmetric apply path for exactly that reviewed set.

Observed flow:

1. workspace worktree add warned that the workspace had hundreds of worktree-like directories and suggested cleanup dry-runs.
2. Ran:

   studio wp datamachine-code workspace worktree cleanup --dry-run --inventory-only --skip-github --format=json

3. The preview reported:
   • would_remove: 38
   • cleanup_buckets.explicit_cleanup_candidates: 38
   • candidates_by_signal.cleanup_eligible: 38
4. User approved cleaning those 38 explicit cleanup-eligible worktrees.
5. Tried to apply the same bounded inventory cleanup without --dry-run:

   studio wp datamachine-code workspace worktree cleanup --inventory-only --skip-github --format=json

6. DMC refused with:

   Inventory-only cleanup is review-only. Pass --dry-run, then run full cleanup to apply a reviewed plan.
   

That refusal is reasonable for safety, but it leaves the operator without a clear way to apply exactly the reviewed cleanup_eligible set.

Why this matters

The recommended next step, "run full cleanup," can expand the decision surface from:

• the 38 explicit lifecycle cleanup candidates just reviewed

into:

• a broader merge/PR signal scan with different candidate discovery behavior.

That makes the safe review surface and safe apply surface asymmetric.

Desired behavior

DMC should offer a clear bounded apply path for the exact category that was reviewed.

Possible shapes:

studio wp datamachine-code workspace worktree bounded-cleanup-eligible-apply --dry-run --limit=50
studio wp datamachine-code workspace worktree bounded-cleanup-eligible-apply --limit=50

or a run-id based workflow:

studio wp datamachine-code workspace cleanup plan --mode=cleanup-eligible --format=json
studio wp datamachine-code workspace cleanup apply <run-id>

Acceptance criteria

• A dry-run that reports explicit cleanup_eligible worktrees prints the exact safe apply command for that same reviewed class.
• The apply path only removes lifecycle cleanup_eligible rows unless the operator explicitly asks for broader full cleanup.
• Apply revalidates dirty worktree, unpushed commits, containment, and primary-safety before deletion.
• Apply does not discover unrelated full-cleanup candidates as part of applying the reviewed bounded set.
• Artifact cleanup remains separate and does not remove dependencies from active worktrees by default.
• Error messages avoid "run full cleanup" when the operator is trying to apply a bounded cleanup-eligible preview.

Related operator note

Artifact cleanup dry-run also reported reconstructable artifacts in active worktrees, including active minion worktrees. That behavior may be technically correct, but should remain opt-in/separate from worktree deletion so cleanup during active parallel work does not disrupt running sessions.