Isolate Bukkit server test mock

[BenCodez]

Summary

• replace the permanent Bukkit.setServer mutation in VoteSiteAdditionalTest with a scoped Mockito static mock
• close the mock after the class so later tests do not mistake the mock server for a registry-capable Bukkit runtime
• preserve production Material.isItem() validation

Regression

This fixes order-dependent failures in ControlInspectionServiceTest.rewardSimulationNormalizesButNeverExecutesTypedActions and BackendConfigurationServiceTest.rewardBuilderPersistsTheTypedSiteProposalAndOnlyReplacesItsSelectedSubtree on current Spigot API snapshots.

Verification

• focused suite: 71 tests passed
• full suite: 496 tests passed
• git diff --check passed

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-31T01:29:22.136776Z	b0a29f9	PR opened
🔒 Security Review	✅ Completed 2026-08-31T01:29:52.285250Z	b0a29f9	PR opened

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