Migrate custom fields

Reinstalls all B2B-related custom field definitions.

bin/console b2b:migrate:custom-fields

Ensures all custom fields are properly registered in the system.

Behavior:

• Runs CustomFieldSetup installation routine

• Updates existing custom field definitions

• Safe to run multiple times (idempotent)

Use Case:

• After plugin updates

• Fixing missing custom field definitions

• Schema synchronization