1.53.1
(fix): Client-level global header options (e.g. option.WithVersion(...) passed
to the root client constructor) are no longer clobbered by env-var or
client-default resolution on every request. Env and client-default
fallbacks are now resolved once at client construction, and per-request
options only override the header when explicitly set. Precedence is:
request-level option > client-level option > env var > client default.