Fix retained post-review status queue echo

[yvette-carlisle]

Summary

• keep retained post-review success-state worktrees out of queued intake status
• show only open tracker blockers in queued candidate blocker lists
• cover prompt-mode internal-review admin merge with a regression test

Verification

• git diff --check
• cargo test -p decodex live_operator_status_snapshot -- --nocapture
• cargo test -p decodex reconcile_post_review_orchestration_runs_admin_merge -- --nocapture
• cargo test -p decodex -- --test-threads=1