The provisional locale fell back to zh, so a browser asking for neither
zh nor en (fr, de) opened the product in Chinese. Resolve to en instead,
and use en as the dictionary fallback: the shipped zh/en dictionaries
declare identical key sets, so one constant serves both roles.
Add scripts/locale-dictionary-parity.spec.ts to gate that symmetry, and
set the asserted locale explicitly in specs that had relied on the old
zh fallback through a dead usePinnedBrowserLanguages call (those files
declare no jsdom environment, so browser detection never ran there).
imccyu