List a vault's members

List the people who hold a role in a vault, oldest grant first, with their role and when they were added.

This is the direct membership list. Someone who can open the vault only through organization-wide visibility is not a member and does not appear here, so a vault that is not access-controlled can be readable by people this list does not name.

Requires the owner role in the vault and the organization-level permission to manage vaults.

Requires a user-scoped API key (u:gcai_...). A vault is shared with named people, so an organization-scoped key has no identity to resolve vault access with.