The background login thread now flips _auth_state to authenticated
itself when a slow tokenstore resume succeeds after the 10s wait --
previously its result landed in an abandoned private queue and the
docstring's promised late recovery never happened, leaving every
subsequent call failing until an explicit authenticate. Guarded to only
ever transition from unauthenticated, so an explicit authenticate/MFA
flow that took over meanwhile is never clobbered; the timeout branch no
longer re-writes the state (a redundant write that could race a success
at the boundary). Structured-log messages reworked alongside.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Christophe Vila
78c494affb