fix(queue): gate strategy mission boss-ready intake

[scarmani]

Summary

• add a fail-closed strategy_mission_gated queue classifier before proof/docs keyword heuristics
• index Epic [Epic] Strategy mission: DecisionReceipt Action wedge and external proof #8665 in the roadmap intake register
• make the canonical queue rule discoverable in NEXT_STEPS_CANONICAL

Validation

• python3 -m pytest tests/swarm/test_proof_first_queue.py tests/swarm/test_proof_first_queue_classification.py
• pre-commit run --files aragora/swarm/proof_first_queue.py tests/swarm/test_proof_first_queue.py tests/swarm/test_proof_first_queue_classification.py docs/status/ROADMAP_INTAKE_REGISTER.md docs/status/NEXT_STEPS_CANONICAL.md
• git push hook: mypy changed aragora files passed

Notes

• Follow-up to the docs(strategy): register mission cadence execution map #8703 Grok dissent: strategy mission cadence / Epic [Epic] Strategy mission: DecisionReceipt Action wedge and external proof #8665 is durable planning truth, not wholesale boss-ready work.
• Draft only; do not merge in this cycle.