FluentCart customers and portal

Treat Customer as the commerce identity and WP_User as an optional login identity. Enforce ownership for every customer-facing object.

Read customer-identity.md before changing email/user links, moving resources, or exposing customer data.

Resolve identity safely

• Customer rows live in fct_customers and may link to WP users by user_id.
• Orders, subscriptions, addresses, licenses, statistics, and labels reference Customer IDs, not WP user IDs.
• CustomerResource::getCurrentCustomer() first resolves the logged-in WP user by user_id or matching email and may attach that user_id to the existing row.
• Passing true may create a Customer from the current WP user.
• Email matching is a linking operation. Validate verified ownership and duplicate/merge consequences before changing an address.