test: add useApi hook tests for loading/ok/error/null/refetch/cancel

[shinzoxD]

Summary

Adds a focused useApi test covering the five behaviours the hook is designed to provide:

1. Starts in loading and resolves to ok with the resolved data
2. Transitions to error with the rejected error's message
3. Short-circuits when path is null — no apiGet call, no state transition
4. refetch() triggers a new apiGet call
5. Unmount cancels the in-flight request — no setState-on-unmounted warning

Why

useApi is the foundation for dashboard fetching but is untested, so the cancellation guard (the cancelled flag in the effect) and the null short-circuit are unverified. This locks both branches down so future refactors of the hook are safe.

Test Plan

• npx jest src/lib/__tests__/useApi — 5/5 pass
• Mocks ../apiClient so the hook is tested in isolation
• Uses renderHook + waitFor + act from @testing-library/react (already in devDeps)

Linked issue

Closes #299

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[shinzoxD]

@mikewheeleer — friendly ping on this fork PR (test: add useApi hook tests for loading/ok/error/null/refetch/cancel).\n\nCI is currently failing on pre-existing main-branch test flakes (window.matchMedia is not a function in ThemeToggle.test.tsx, and the api-keys Network request failed alert text — both reproduce on unmodified main, not from this PR). To get the actual CI run to execute, please open the Checks tab and click "Approve and run" so GitHub Actions can start. Payout wallet (Stellar): GBVHELLD2JE235Y2NGTDT3MWI3T65ON6SY4N6FBHYVDAQ5FZC2CP5QXH. Thanks!

[mikewheeleer]

thanks for the PR @shinzoxD! 🙏 issue #299 isn't assigned to you — please get the issue assigned to you first (claim it), then raise the PR. closing as invalid for now; would love to see it back once you're assigned 🙌