Verify sticky behavior + scroll-up button per TZ Table 22
PageLayout.test: assert header/breadcrumbs/title stay outside sticky
wrapper, filter column carries __column-left (CSS sticky on desktop),
stickyContent (day-tabs) gets __sticky-content wrapper, overlay only
when stickyContent present.
ScrollUpButton.test: assert button hidden below 300px threshold, visible
above it, disappears on scroll-back, correct aria-label/type, listener
cleaned up on unmount.
All 27 tests pass; no implementation changes needed — React matches
Angular reference behavior exactly.
gnezim
f6def717b5