Fix PoW status message never rendering in the browser

A tight loop of only-awaited crypto.subtle.digest calls never yields
to the browser's rendering pipeline (they resolve as microtasks), so
the "computing proof of work" status update was silently skipped from
the user's perspective even though the computation ran correctly.
Insert an explicit macrotask yield before and periodically during the
search so the message actually paints and the tab stays responsive.

0 files changed, 0 insertions, 0 deletions