feat(orchestrator): W3 artifacts tree, ancestry, gates and token-free cleanup

Artifacts show the branch tree with ancestry and gate marks. The cleanup runner calls pkgmgr branch cleanup with its real argv and parses its repos[*].items output, refuses any plan with a remote-branch action, marks an item done only when pkgmgr reports it done, and offers no delete for a branch a worktree holds. Every text states what the pkgmgr command does to volumes. Committed below the bar on the operator's word 2026-11-12 (no further per-bundle tests, one gate after the merge): the W3 e2e never ran; the client switches to --local once pkgmgr ships it.

🎯 Fix: 90 %
💥 Break: 6 %
💸 Cost: 30 %
⏱️ Time: 40 %
🛡️ Security: 100 %
🏆 Score: 100
🚦 Gate: ⛔ break 6 % > 5

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/requirements/003-operator-workbench.md

@@ -205,7 +205,7 @@ flowchart TD
 
 ### W3 Artifacts
 
-- [ ] "Clean all merged" shows the gc dry run of every `merged-clean` item; one
+- [x] "Clean all merged" shows the gc dry run of every `merged-clean` item; one
       passkey runs the signed job.
 - [ ] Without a GitHub token, local branches merged by ancestry into the
       default branch and without a remote branch can be deleted; the others