Enhance NaturalUser proto model and StripeAccountApi to support optional organization name, extensible additionalProperties map, and automatic Stripe Tax ID registration based on country-resolved VAT type. Refactors createOrUpdatePaymentAccount to move birthday validation inside COLLECTOR branch only. Pre-requisite for Story 5.10b (licensing infrastructure).
Enhance NaturalUser proto model and StripeAccountApi to support optional organization name, extensible additionalProperties map, and automatic Stripe Tax ID registration based on country-resolved VAT type. Refactors createOrUpdatePaymentAccount to move birthday validation inside COLLECTOR branch only. Pre-requisite for Story 5.10b (licensing infrastructure).