feat: add policy simulation sandbox

[basseyanam03-dev]

Close #39

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[vercel]

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[mergekeeper]

MergeKeeper review

Scope: in scope for linked issue #39.
Verdict: clean

The policy simulation sandbox feature is correctly implemented according to the requirements and issue description.

Reviewed commit: b73bbc9848a9acce1e3d63cee2123c11312c01c7.
CI and merge eligibility are checked separately.

[mergekeeper]

Approved

Successfully implemented the interactive policy simulation sandbox and rule tester matching all acceptance criteria.

[mergekeeper]

MergeKeeper merge status

Status: blocked
PR state: open
Mergeability: mergeable
Checked commit: b73bbc9848a9acce1e3d63cee2123c11312c01c7.

Reason:
GitHub pull request merge request failed with 405: 3 of 3 required status checks have not succeeded: 2 expected.

Next steps:
This required status check is enforced directly by the repository's branch rules, independent of MergeKeeper's own CI evaluation — a maintainer merge override cannot bypass it unless MergeKeeper is authorized to.

1. Wait for the check to pass, or fix the underlying failure.
2. To let an explicit override bypass this check going forward, add the MergeKeeper GitHub App as a Bypass actor on the ruleset (Settings → Rules → Rulesets → the ruleset → Bypass list).

[mergekeeper]

Approved

The policy simulation sandbox feature is correctly implemented according to the requirements and issue description.