The const.py comment claimed an empty stored token yields a client that
answers 401 until configured, but NestQuestApiClient raises ValueError
at construction for an empty/whitespace token. Keep the fail-fast guard,
correct the documentation to state the actual contract (default token is
the empty string; options flow validates non-empty; the coordinator must
configure a token first or handle the construction error), and add a
test pinning that client_from_entry with an unconfigured entry raises at
construction instead of building a client that can only 401.
overseer
b6b1ab1934