Fix flaky pending-prompt transcript test

[eivindjonassen]

Summary

Keep the REST refetch's act() scope open through React Query's zero-delay observer notification timer. Awaiting the refetch alone updates the cache but can leave React's rendered pending row unchanged when the assertion starts.

This caused repeated CI failures and blocked post-merge publication for #46. The change is test-only; it does not increase assertion timeouts or change app behavior.

Verification

• Reproduced the exact failing assertion with Node's JIT disabled before the fix.
• Passed 10 consecutive JIT-disabled focused test runs after the fix.
• Rebased onto current main with OpenCode 2.0.21 and reran the focused JIT-disabled test successfully.
• pnpm check passed on current main, including lint, typecheck, tests, and both Hermes exports.
• pnpm native:doctor passed all 18 checks.