Add unit tests for AED status state machine transitions

[vgpastor]

Context

The AED status state machine in src/lib/aed-status.ts validates transitions between statuses (DRAFT → PENDING_REVIEW → PUBLISHED → INACTIVE, etc.) but lacks comprehensive unit test coverage.

What needs to happen

• Write unit tests for validateStatusTransition() covering all valid transitions
• Test that invalid transitions are rejected
• Test edge cases (same status → same status, null inputs)

Where to look

• src/lib/aed-status.ts — The state machine implementation
• tests/unit/ — Where tests go

Tech

• Vitest (not Jest)
• Follow AAA pattern (Arrange → Act → Assert)
• Test naming: should[ExpectedBehavior]When[Condition]

Acceptance criteria

• All valid transitions tested
• All invalid transitions tested
• Edge cases covered
• Tests pass with npm run test:unit