*Bug description*
Group field value not added on blur, Add user, or Next actions

1. 1. Summary
      When typing a value in the "Groups" field in the Users customization step, the value is only added to the list when pressing Enter. The value should also be added when:

• Blurring the field (clicking outside)
• Clicking "Add user" button
• Clicking "Next" button

*Reproduction steps*
Steps to reproduce the behavior:
1. Navigate to the Create Image Wizard
2. Go to the "Users" step
3. Type a group name in the "Groups" field (e.g., "admin")
4. *Do NOT press Enter*
5. Try one of the following:

• Click outside the field (blur)
• Click "Add user" button
• Click "Next" button
  6. Observe that the group value is NOT added to the list

1. 1. Expected Behavior
      The group value should be automatically added to the list when:

• The user blurs the field (clicks outside)
• The user clicks "Add user" button
• The user clicks "Next" button
  *Expected behavior*
  A clear and concise description of what you expected to happen.

1. 1. Actual Behavior
      The group value is only added when explicitly pressing Enter. If the user forgets to press Enter or expects the value to be saved automatically, the value is lost.

GitHub Issue: https://github.com/osbuild/image-builder-frontend/issues/3943