Move the SelectedAccount = Accounts.FirstOrDefault(...) lookup from
OnInitialized to OnParametersSet so the preselection tracks the
Accounts list arriving asynchronously (every caller now passes []
first and hydrates after an await). Idempotent — the OnSelectedChanged
callback path returns the same AccountId back and the parent re-render
lookup finds the same account.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
