chore(frontend): add unit tests for `RunUtils.ts`

[puwun]

Chore description

frontend/src/lib/RunUtils.ts provides utility functions for working with run-related data (extracting metrics, getting experiment references, etc) but has no corresponding test file.

We should add a RunUtils.test.ts file to cover these utilities and ensure they behave as expected.

Labels

/area frontend

/area testing

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[puwun]

/assign