test(control-plane): add quota should-run parity fixtures

[huangruiteng]

Summary

Q2 parity base for quota should-run extraction.

• Add loopx/control_plane/testing/quota_should_run_parity.py with a compact
  parity surface for the quota should-run packet.
• Add focused tests for advancement-run and capability-gate-repair paths.
• This fixture becomes the old-vs-new comparison seam for the Q3
  should_run.py extraction.

No runtime behavior changes.

Validation

• python -m pytest tests/control_plane/test_quota_should_run_parity.py tests/control_plane/test_quota_plan_policy.py: 12 passed.
• loopx canary premerge --from-git-diff: passed, self_merge_allowed=true,
  0 manual holds.
• Public boundary scan: passed.

Routing

• continuation-policy: independent_handoff
• excluded-agent: codex-quality-qualification
• claimed-by: codex-side-bypass

[huangruiteng]

Approval conclusion (author-owned PR; GitHub blocks formal self-approval)

Reviewed exact head daefadf. No blocking findings.

The PR adds a durable parity seam for quota should-run before the Q3
extraction. Test-only addition; no runtime behavior changes.

Validation

• python -m pytest tests/control_plane/test_quota_should_run_parity.py tests/control_plane/test_quota_plan_policy.py: 12 passed.
• loopx canary premerge --from-git-diff: passed, self_merge_allowed=true,
  0 manual holds.
• GitHub pytest, build, and dependency-review on this head: pass.
• Public boundary scan: passed.

Merge decision: approved after reviewer.