fix: forward async isInstallationPure into wizard model

The wizard flow opens the reporter before populateReporterDataAsync
completes, so isInstallationPure defaults to true and is never updated
in the overlay's internal model. Add a whenDataComplete promise that
resolves after all async data is populated, and forward the resolved
isInstallationPure value into the wizard via updateModel.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>