Resolve jest/expect-expect warnings

[pmcelhaney]

Address jest/expect-expect warnings by adding explicit assertions or using approved assertion patterns for helper-driven tests.

Context and motivation

Some tests rely on side-effect or thrown-error pathways that are not always detected by the rule. We should make assertions explicit where practical.

Acceptance criteria

• Current warning sites are triaged
• Tests that can include direct assertions are updated
• Legitimate helper patterns are configured or suppressed in a narrow, documented way
• Net warning count for this rule is reduced