refreshStatus computes the status line on the calling goroutine (as
before) but now writes it to the status view in an
onUIThreadUnlessRepoChanged bounce rather than calling SetViewContent
directly from the worker. RefreshingStatusMutex is left in place for now;
it only guards the compute phase between concurrent callers and comes out
in the mutex cleanup.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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