Add dashboard chrome to POS and collapsible sidebar

Wrap the POS terminal in the sidebar + topbar layout via a nested
fullscreen layout, and make the sidebar collapse to an icon-only rail
with a persisted toggle so operators keep navigation on the POS screen.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/dashboard/src/app/[locale]/(fullscreen)/pos/page.tsx

@@ -1,16 +1,11 @@
 import { Suspense } from "react";
-import { CafeThemeProvider } from "@/components/theme/cafe-theme-provider";
 import { PosScreen } from "@/components/pos/pos-screen";
 
-/** Full-viewport POS terminal — no sidebar, no topbar. */
+/** POS terminal — chrome (sidebar + topbar) is provided by layout.tsx */
 export default function PosPage() {
   return (
-    <CafeThemeProvider>
-      <div className="flex h-screen min-h-0 flex-col overflow-hidden bg-background p-4 md:p-6">
-        <Suspense fallback={null}>
-          <PosScreen />
-        </Suspense>
-      </div>
-    </CafeThemeProvider>
+    <Suspense fallback={null}>
+      <PosScreen />
+    </Suspense>
   );
 }