setNavigationBarBackgroundColor was never called on the 15 screens
adopted in 3456184, so it stayed at the default .clear and the real
window background (black) showed through. Set it to
AppColors.backgroundLight on all of them, matching each screen's own
actual content background. Also wraps CartView's title in
LCENavigationView for consistency with the rest of the app - no
setLeftButton since Cart is a tab root, no back button needed.
The other reported bug (empty right-button slot rendering a visible
glass circle) is fixed in LCEssentials itself (separate repo,
commit 8b0f650 on fix/navigation/liquid-glass-button-chrome) but
won't take visual effect here until that's published and this
repo's Package.resolved is bumped to point at it.
Standardizes the back button to a single shared component
(AppBackButtonIcon, 32x32/14pt) instead of ~16 hand-duplicated
52x52/24pt copies, and wires each screen through LCENavigationView
per this project's mandatory-usage rule. Home and Store Detail
intentionally excluded - both have bespoke header designs (collapsing
header, hero-image overlay) this change would visually disrupt.
