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.
