- Zustand sidebar store with persist middleware (collapse/expand, mobile open)
- Sticky header with logo, breadcrumb, theme toggle, locale switcher, user avatar
- Collapsible sidebar with Dashboard/Marketplace nav, accordion categories, footer
- Mobile responsive: hamburger menu with overlay sidebar on small screens
- Theme toggle cycling light/dark/system with mounted guard
- Locale switcher setting NEXT_LOCALE cookie with router.refresh
- Empty dashboard state with grid icon, "Keine Widgets aktiv" text, add button
- AppShell composing header + sidebar + responsive main content area
- All user-visible strings via useTranslations (UI-03 compliance)
schalli
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