library: mobile polish for cover, toolbar, shelf, overview & share panel - Home/InteractiveCover: disable hotspots on mobile, fixed 448px cover band, center the "What is this place?" button 22px below the header - Header/UserProfile: stop the fixed header clipping the profile dropdown - LibraryToolbar + Library layout: connect the toolbar to the header, left-align toolbar actions on mobile - Shelf: two-row header on mobile, widen the shelf banner, advance one object per carousel arrow click - ObjectOverviewModal: stop grid rows stretching to fill the full-height body - ShareSelectionPanel: stack action buttons with 14px single-line labels on mobile #154