[XY-902] Fix stale closeout lease target dispatch

[yvette-carlisle]

Summary

• allow status-visible closeout lanes to reuse the same issue's stale active closeout lease instead of treating it as a competing claim
• prioritize status-visible retained closeout dispatch for targeted runs before normal/retry fallback
• add a regression covering a merged PR lane with a stopped active closeout process

Validation

• cargo test -p decodex targeted_identifier_dispatch -- --nocapture
• cargo make check-rust
• cargo make check (passed after repo-local npm ci in site/; 1036 nextest tests passed, 1 skipped)