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/messages/ar.json

@@ -58,6 +58,8 @@
   },
   "nav": {
     "aria": "القائمة الرئيسية",
+    "collapseSidebar": "طي الشريط الجانبي",
+    "expandSidebar": "توسيع الشريط الجانبي",
     "groups": {
       "operations": "العمليات اليومية",
       "menuSales": "القائمة والمبيعات",
@@ -945,7 +947,28 @@
     "featureDiscover": "ملف الاكتشاف (ذكاء اصطناعي)",
     "featureOn": "مفعّل",
     "featureOff": "غير متاح — ترقية",
-    "featureMenu3dUpgrade": "القائمة 3D متاحة في برو وما فوق."
+    "featureMenu3dUpgrade": "القائمة 3D متاحة في برو وما فوق.",
+    "checkout": {
+      "title": "الفاتورة والدفع",
+      "subtitle": "راجع طلبك وادفع",
+      "backToPlans": "العودة إلى الخطط",
+      "invalidPlan": "الخطة المحددة غير متاحة للشراء عبر الإنترنت.",
+      "invoiceLabel": "فاتورة مبدئية",
+      "invoiceNo": "رقم الفاتورة",
+      "issuedAt": "تاريخ الإصدار",
+      "billingPeriod": "مدة الاشتراك",
+      "monthsCount": "{count} شهر",
+      "description": "الوصف",
+      "qty": "الكمية",
+      "unitPrice": "سعر الوحدة",
+      "amount": "المبلغ",
+      "planLine": "اشتراك خطة {plan}",
+      "subtotal": "المجموع الفرعي",
+      "total": "المبلغ المستحق",
+      "secureNote": "تتم المعالجة عبر بوابة دفع بنكية آمنة.",
+      "payTotal": "ادفع {total}",
+      "redirecting": "جارٍ التحويل إلى البوابة..."
+    }
   },
   "settings": {
     "title": "الإعدادات",

web/dashboard/messages/en.json

@@ -69,6 +69,8 @@
   },
   "nav": {
     "aria": "Main navigation",
+    "collapseSidebar": "Collapse sidebar",
+    "expandSidebar": "Expand sidebar",
     "groups": {
       "operations": "Daily operations",
       "menuSales": "Menu & sales",
@@ -1017,7 +1019,28 @@
     "featureOff": "Not included — upgrade",
     "featureMenu3dUpgrade": "3D menu is available on Pro and higher plans.",
     "featureMenuAi3d": "AI 3D generation",
-    "featureMenuAi3dUpgrade": "AI 3D generation is on Business and Enterprise (100 per month)."
+    "featureMenuAi3dUpgrade": "AI 3D generation is on Business and Enterprise (100 per month).",
+    "checkout": {
+      "title": "Invoice & Payment",
+      "subtitle": "Review your order and pay",
+      "backToPlans": "Back to plans",
+      "invalidPlan": "The selected plan is not available for online purchase.",
+      "invoiceLabel": "Proforma invoice",
+      "invoiceNo": "Invoice no.",
+      "issuedAt": "Issued",
+      "billingPeriod": "Billing period",
+      "monthsCount": "{count} mo",
+      "description": "Description",
+      "qty": "Qty",
+      "unitPrice": "Unit price",
+      "amount": "Amount",
+      "planLine": "{plan} plan subscription",
+      "subtotal": "Subtotal",
+      "total": "Amount due",
+      "secureNote": "Payment is processed through a secure bank gateway.",
+      "payTotal": "Pay {total}",
+      "redirecting": "Redirecting to gateway..."
+    }
   },
   "settings": {
     "title": "Settings",

web/dashboard/messages/fa.json

@@ -69,6 +69,8 @@
   },
   "nav": {
     "aria": "منوی اصلی",
+    "collapseSidebar": "جمع کردن نوار کناری",
+    "expandSidebar": "باز کردن نوار کناری",
     "groups": {
       "operations": "عملیات روزانه",
       "menuSales": "منو و فروش",
@@ -1018,7 +1020,28 @@
     "featureOff": "غیرفعال — ارتقا دهید",
     "featureMenu3dUpgrade": "منوی ۳D در پلن حرفه‌ای و بالاتر فعال است.",
     "featureMenuAi3d": "تولید ۳D با AI",
-    "featureMenuAi3dUpgrade": "تولید ۳D با هوش مصنوعی در پلن کسب‌وکار و سازمانی (۱۰۰ بار در ماه) فعال است."
+    "featureMenuAi3dUpgrade": "تولید ۳D با هوش مصنوعی در پلن کسب‌وکار و سازمانی (۱۰۰ بار در ماه) فعال است.",
+    "checkout": {
+      "title": "پیش‌فاکتور و پرداخت",
+      "subtitle": "جزئیات سفارش را بررسی و پرداخت کنید",
+      "backToPlans": "بازگشت به پلن‌ها",
+      "invalidPlan": "پلن انتخاب‌شده برای خرید آنلاین معتبر نیست.",
+      "invoiceLabel": "پیش‌فاکتور",
+      "invoiceNo": "شماره فاکتور",
+      "issuedAt": "تاریخ صدور",
+      "billingPeriod": "مدت اشتراک",
+      "monthsCount": "{count} ماه",
+      "description": "شرح",
+      "qty": "تعداد",
+      "unitPrice": "قیمت واحد",
+      "amount": "مبلغ",
+      "planLine": "اشتراک پلن {plan}",
+      "subtotal": "جمع جزء",
+      "total": "مبلغ قابل پرداخت",
+      "secureNote": "پرداخت از طریق درگاه امن بانکی انجام می‌شود.",
+      "payTotal": "پرداخت {total}",
+      "redirecting": "در حال انتقال به درگاه..."
+    }
   },
   "settings": {
     "title": "تنظیمات",