Expand description
SDK identity types — re-exported from ppoppo-sdk-core.
Phase A (RFC RFC_2026-05-08_app-credential-collapse.md) lifted
these primitives out of pas-external so multiple SDK crates and
1st-party services share the same definitions. Consumers reach the
same names through pas_external::types::* or pas_external::*
(top-level re-export); the relocation is invisible at the SDK
surface.