Fix Hardhat ReimbursementPool fixture gap for WalletRegistryGovernance tests

[mswilkison]

The security hardening PR for non-sensitive findings added/updated Solidity coverage for:

• Finding 12: allowlist weights deployment should fail if ownership transfer fails.
• Finding 13: WalletRegistryGovernance.finalizeAuthorizationDecreaseDelayUpdate should preserve the authorization decrease change period.

During local validation, npx hardhat compile succeeds, but a focused Hardhat test run for WalletRegistryGovernance does not reach the test cases because the hardhat-deploy fixture fails before test execution:

ERROR processing deploy/00_resolve_reimbursement_pool.ts:
Error: deployed ReimbursementPool contract not found

This blocks end-to-end runtime validation for the governance/deployment portions of the PR even though compile and formatting checks pass.

Suggested follow-up:

• Repair or document the local fixture setup needed for WalletRegistryGovernance.test.ts.
• Ensure the dependency deployment record for ReimbursementPool is available in the test fixture path.
• Add a short validation note to the testing docs or package README so future reviewers can run focused Hardhat tests without rediscovering the setup gap.

[linear]

ENG-646