GET /v1/connections/user returns {connections, user_id} (the per-provider connected-account list). Schema kept open pending a normalize-to-accounts migration.
GET /v1/connections/user
{connections, user_id}
accounts
@type t() :: %Spatio.Model.ConnectionAccountListResponse{ accounts: [map()] | nil, connections: [map()] | nil, user_id: String.t() | nil }