Fix customer contact user type invariant

[roncodes]

Summary

• enforce the FleetOps customer invariant from the internal contact save flow: contact.type=customer normalizes the linked user to user.type=customer
• prevent existing customer contacts from being changed away from type=customer
• add an idempotent repair migration for historical customer contacts and strong Fleet-Ops Customer role hints

Root cause

FleetOps console/internal customer creation goes through the generic internal contact controller, which could persist a contact with type=customer while leaving the associated user as a normal user/contact. Customer identity should come from the contact/user type pair, not from order-customer polymorphism or roles.

Notes

• Order customer handling is intentionally untouched; a normal contact may be an order customer without becoming a FleetOps customer.
• The Fleet-Ops Customer role is only used in the migration as historical repair evidence, not as runtime source of truth.

Verification

• php -l on touched PHP files
• targeted PHP CS Fixer dry-run on touched files
• git diff --check

Known gap

• composer test:unit is blocked in this checkout because the local Pest install under server_vendor is missing its nested vendor autoload.