fix(ci): make gate freshness issue lifecycle resilient

[proggeramlug]

Summary

• use GitHub REST endpoints for the gate-freshness sticky issue instead of GraphQL-backed gh issue commands
• find closed as well as open alerts and reopen the newest canonical issue on recurrence
• sabotage-test reopening, closing, and recovery-comment ordering

Diagnosis

#8312 fixed #8085’s freshness classification, and the next two scheduled sweeps found every gate fresh. Both sweeps still left #8085 open because GitHub’s GraphQL service returned 503 from gh issue close / gh issue list, while the REST API remained healthy.

The old open-only lookup also contradicted the “one sticky issue forever” invariant: after a successful close, a later stale episode would create a duplicate instead of reopening the maintained issue.

Fixes #8085.

Validation

• python3 scripts/check_gate_freshness.py --self-test
• python3 scripts/check_gate_freshness.py --dry-run
• python3 scripts/gc_gate_wiring_check.py
• python3 scripts/ci_plan.py --self-test
• python3 -m py_compile scripts/check_gate_freshness.py
• actionlint .github/workflows/gate-freshness.yml
• git diff --check

No version files changed.