Add initial high-value unit tests

### Description

Implement the initial agreed unit-test coverage for high-value behavior, utilities, transforms, and components identified during the audit.

### Action Items

- [ ] Select the highest-value targets from the audit.
- [ ] Add focused tests for expected and edge-case behavior.
- [ ] Use shared test utilities and conventions.
- [ ] Confirm tests provide meaningful regression protection.

### Additional Information

Parent Epic: https://github.com/hackforla/lucky-parking/issues/732

Start by reading the audit and the parent epic at issue #732 to identify the agreed high-value targets. Then review the repository's shared test utilities and conventions before selecting utilities, transforms, and components. Done means focused expected- and edge-case tests are added and provide meaningful regression protection.

Written by the indexing model from the issue text.