🧪 Migrate Tests from Hand-Rolled Mocks to Mockito @Mock

[sfloess]

Problem

Tests use hand-rolled mock implementations instead of Mockito annotations.

Solution

Replace manual mocks with Mockito:

• Use @Mock annotations
• Add @ExtendWith(MockitoExtension.class)
• Use when(), verify() methods

Modules to Update

• jplatform-security
• jplatform-monitoring
• jplatform-threadpool
• jplatform-core

Benefits

• Less boilerplate
• Standard patterns
• Better maintainability

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Priority: MEDIUM | Testing Refactoring