Principal identity is the subject (who), not the credential instance
(which token). The hashID suffix was an internal cache fingerprint that
leaked into the public ID. Callers that need to distinguish individual
token instances must use a separate mechanism.
TSV serialization in ToRecord() still writes Name~hashID when hashID is
set so the credential file round-trips correctly.
Guards against the v1.2.4 bug (fixed in c32acd5) where Authenticate
held a.mux via defer for its full duration, then called
loadAndVerifyToken which also tries to acquire a.mux — deadlock on
every token auth request.
TestAuthenticateTokenNoDeadlock exercises both the bare-token
("", token) and named-username ("api", token) forms with a 1s
timeout, so a regression fails fast rather than hanging the suite.
