Wrap title + filters in a sticky container (top-8 sm:top-12, z-20, bg-white)
on all pages for consistent scroll behavior. Also fix SidebarTimer icon
visibility when sidebar is collapsed.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Introduces SidebarLink component, UI store with localStorage persistence,
and smooth CSS transitions between expanded (w-64) and compact (w-16) modes.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>