Wizard blocks advance on save failures

Certificate wizard now prevents advancing to the next step if saving your progress fails, protecting unsaved work.

Bug Fixes

The certificate wizard previously allowed you to advance to the next step even if saving the current step's data failed silently. Now the wizard blocks step progression if a save error occurs, and displays a clear error message explaining what went wrong. This prevents data loss and ensures each step is successfully persisted before moving forward. Save and exit operations also properly wait for completion before closing the draft.