XY-873: Implement autonomous architecture recovery

[yvette-carlisle]

Summary

• add autonomous architecture recovery packets and boundary checks for loop guardrail stops
• allow one bounded within-authority architecture recovery retry before human-required terminalization
• surface recovery evidence in prompts, private evidence readback, harness feedback, specs, and runbook docs

Validation

• cargo make fmt
• cargo make lint-fix
• cargo make test: 1033 passed, 1 skipped
• git diff --check

Recovery note

• Original Decodex run reached validation-ready evidence, then remained idle without terminal handoff. Operator used lane-control hard interrupt fallback, preserved the retained worktree, reran the repo gate, and created this PR from the same XY-873 branch.