fix(evidence): persist prepared quorum artifacts

[scarmani]

Summary

• add collect-evidence --out for dry-run JSON artifact persistence
• allow exact prepared artifacts to be reused with the existing --prepared-json apply path instead of rerunning slow reviewers
• reject --out with --apply so artifact writing stays prepare-only

Live context

• chore(deps): Bump mermaid from 11.15.0 to 11.16.0 in /aragora/live #8680 dry-run produced supportive Claude+Grok evidence at exact head 6d62986
• direct --apply then timed out before posting, leaving comments empty and merge-quorum still missing evidence
• this repair makes the safe path explicit: dry-run once with --out, inspect/lint, then apply the exact artifact through --prepared-json

Validation

• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 /Users/armand/.pyenv/versions/3.11.11/bin/python -m pytest -q tests/swarm/test_quorum_evidence.py tests/cli/commands/test_review_queue.py::TestCommandDispatch::test_parser_registers_build_packet_run_and_act
• /Users/armand/.pyenv/versions/3.11.11/bin/python -m ruff check aragora/swarm/quorum_evidence.py scripts/collect_quorum_evidence.py aragora/cli/commands/review_queue.py aragora/cli/parser.py tests/swarm/test_quorum_evidence.py tests/cli/commands/test_review_queue.py
• /Users/armand/.pyenv/versions/3.11.11/bin/python -m ruff format --check aragora/swarm/quorum_evidence.py scripts/collect_quorum_evidence.py aragora/cli/commands/review_queue.py aragora/cli/parser.py tests/swarm/test_quorum_evidence.py tests/cli/commands/test_review_queue.py
• bash scripts/automation_pr_preflight.sh origin/main HEAD

[scarmani]

Closing this draft as part of the queue-drain substrate freeze path.

Reason: this PR changes evidence/quorum tooling (collect_quorum_evidence.py). The current drain mission explicitly avoids substrate meta-work; this draft has no active lane owner, no unread steering, no reviews, and a clean local worktree at the pushed head. Keeping it open adds merge-quorum/tooling queue pressure without an autonomous drain path in this loop.

No branch deletion was requested; branch codex/collect-evidence-prepared-artifact-20260629 and the local worktree are preserved for recovery if the operator wants to revive this tooling change outside the drain loop.

Head closed: e75a3bc7247f728e16614ab4c95e5b7c6cf1ef58.