Fixes #675 (the recurring Nightly hardening Windows UI accessibility failure).
Root cause: themes-and-motion.spec.ts opened Preferences and immediately called selectOption("zh-CN") on a <select> that is only rendered on the General page. Preferences defaults to Library (or Online Sources when a registry is linked), and hidden pages are unmounted, so Playwright waited 30s for a control that was not in the DOM. This showed up as locator.selectOption timing out at line 130, on both Chromium and WebKit, for three consecutive main nightlies.
Change: select the General tab, wait for #settings-language to be visible, then change the locale. No product UI change.
Evidence from the 2026-11-09 nightly artifact: the Accessibility snapshot and screenshot show Preferences open on the Library tab, with General listed but not selected. (run)
The simplified Chinese accessibility test now selects the General tab, waits for #settings-language to be visible, and then selects zh-CN. This avoids trying to change the language while the control is not mounted on the initially selected Preferences tab.
