Add reusable SuccessDialogComponent (green check, gradient hero, pop-in
animation) and redesign ErrorDialogComponent to match (red exclamation,
clear title, centered OK). Wire edit-user submit flow to the new dialogs:
success defers navigation until the user confirms, errors surface the
backend message in the styled modal instead of a grey snackbar.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
