feat(cms): implement multi-language support across frontend and admin UI

apps/spa/src/locales/en/translation.json

@@ -12,6 +12,9 @@
     "findMyScent": "Find My Scent ✨",
     "promotions": "Promotions",
     "profile": "My Profile",
+    "signedInAs": "Signed in as",
+    "logout": "Logout",
+    "login": "LINE Login",
     "search": {
       "title": "Search Collection",
       "placeholder": "Search scents, categories...",
@@ -55,5 +58,47 @@
     "moreRelated": "More {{category}}",
     "reviews": "Reviews",
     "viewDetails": "View Details →"
+  },
+  "checkout": {
+    "title": "Checkout",
+    "shippingInfo": "Shipping Information",
+    "fullName": "Full Name *",
+    "phoneNumber": "Phone Number *",
+    "emailAddress": "Email Address *",
+    "shippingAddress": "Shipping Address *",
+    "selectProfileAddress": "Select address from profile:",
+    "confirmOrder": "Confirm Order",
+    "orderSummary": "Order Summary",
+    "discountCode": "Discount Code",
+    "placeholderDiscount": "e.g. SUMMER2026",
+    "apply": "Apply",
+    "remove": "Remove",
+    "usePoints": "Use Loyalty Points",
+    "pointsAvailable": "{{points}} Points Available",
+    "applyPoints": "Apply points discount",
+    "pointsDiscount": "Points (-฿{{points}})",
+    "subtotal": "Subtotal",
+    "shippingFee": "Shipping Fee",
+    "shippingDiscount": "Shipping Discount",
+    "coupon": "Coupon",
+    "pointsRedeemed": "Points Redeemed",
+    "total": "Total",
+    "invalidCoupon": "Invalid coupon",
+    "errorValidating": "Error validating coupon",
+    "failedOrder": "Failed to place order",
+    "errorOccurred": "An error occurred. Please try again."
+  },
+  "hero": {
+    "defaultTagline": "Vibrant Elegance Collection",
+    "exploreCollection": "Explore Collection",
+    "learnMore": "Learn More"
+  },
+  "newsletter": {
+    "defaultTitle": "Begin Your Wellness Journey",
+    "articleDefaultTitle": "Scent Guide Article",
+    "byAuthor": "By {{author}}",
+    "subscribing": "Submitting...",
+    "thankYou": "Thank You for Subscribing",
+    "successMessage": "You have successfully joined our newsletter list. We will send you exclusive sensory privileges soon."
   }
-}
+}