Changes:
- Updated when Stripe customers are created for users who sign up on the
website. A Stripe customer will be created for new users if they
purchase a self-service Fleet Premium license.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Stripe customer accounts are now created during checkout instead of at
signup, deferring billing setup until needed.
* Signup no longer creates a Stripe customer record as part of user
registration.
* Checkout now enforces billing feature availability and includes
improved handling when creating customer billing records.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Eric
d90f8dfd27