MOBILE-SHELL-PARITY defect 2. PrimeVue's default drawer header close-X was
leaking through 'header: hidden' (non-important 'hidden' lost to PrimeVue's
base .p-drawer-header display in stylesheet order) and overlapping the brand
row. Force-hide it with the important variant '!hidden' (matching the file's
existing !w-64), and provide the mobile close affordance in SidebarHeader's
brand row: on mobile the top-right control renders an X ('Sluit menu') and
closes the drawer (handleCollapseClick already calls setMobileOpen(false) on
mobile), mirroring the slot the desktop sidebar uses for its collapse chevron.
Single, non-overlapping close control; showCloseIcon is left at its default.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>