Register proposal 0012 runtime realization

[SoundBlaster]

Summary

• What changed? Registered Proposal 0012 as runtime-realized by the existing pending-review staging and freshness-check runtime.
• Link related issue/task (if any): make next-move selected Proposal 0012 / runtime_realization after Register proposal 0011 runtime realization #391.

Motivation

• Why is this change needed? True review barrier mechanics already exist in supervisor runtime, but Proposal 0012 was still reported as lacking runtime realization.
• What problem, gap, or user need does it address? Removes stale proposal runtime pressure and lets the graph advance to the next backlog item.

Goals

• What should this PR achieve? Mark Proposal 0012 runtime, validation, and observation coverage as complete.
• What is intentionally out of scope? No change to review-gate behavior and no canonical spec mutation.

Changes

• Added Proposal 0012 to tools/proposal_runtime_registry.json with pending-review staging, digest/freshness, and accepted-canonical markers.
• Added a focused regression asserting Proposal 0012 has no remaining runtime next gap.

Validation

• Tests added/updated for changed behavior
• Local checks passed

Commands run:

python3 -m pytest -q tests/test_supervisor.py -k 'proposal_0012 or proposal_0011 or proposal_runtime_index or review_pending or resolve_gate_approve'
git diff --check
python3 -m json.tool tools/proposal_runtime_registry.json >/dev/null
make backlog
make next-move

Results:

• Focused tests: 18 passed, 595 deselected.
• Backlog after this slice: entry_count = 27, runtime_realization = 18.
• Next move advances from Proposal 0012 to Proposal 0013 / runtime_realization.
• Pre-commit hooks passed during commit.

Risks / Notes

• Backward compatibility impact: none; registry metadata and regression only.
• Migration/config changes required: none.
• Known limitations: the next proposal runtime backlog item is Proposal 0013.

Checklist

• PR title clearly describes the change
• Scope is focused and minimal
• Documentation updated (or N/A)
• No secrets or sensitive data added

[SoundBlaster]

Independent stack review from #390: no blocking findings. I checked the PR-local diff against its stacked base, verified the Proposal 0012 registry entry points at existing pending-review barrier runtime/validation/observation markers, and confirmed the focused proposal runtime tests/checks are green in the stack context.

[SoundBlaster]

Independent stack review from #390: no blocking findings. I checked the PR-local diff against its stacked base, verified the Proposal 0012 registry entry points at existing pending-review barrier runtime/validation/observation markers, and confirmed the focused proposal runtime tests/checks are green in the stack context.