feat: full UI redesign with design system, Nielsen heuristics compliance

- Install lucide-react, framer-motion, react-hot-toast, clsx, tailwind-merge
- Custom Tailwind config: semantic color tokens, Inter font, shadow scale,
  border radius scale, custom animations (fadeIn, slideUp, shimmer)
- Shared component library: Button, Badge, Card, Input, Select, Textarea,
  EmptyState, Skeleton, LoadingSpinner
- Global CSS with @layer components (.btn, .card, .input, .badge, .skeleton)
- Toast notification system via react-hot-toast + showToast utility
- ErrorBoundary wrapper for graceful error recovery
- Redesigned navigation: sticky, active state indicators, Lucide icons
- Dashboard: hero header, today highlighting, scrollable week grid,
  redesigned meal cards, empty states, skeleton loading
- Meal Detail: hero image with gradient overlay, metadata row with icons,
  Lucide star rating, edit-existing-feedback flow
- Pantry: inline add form, search/filter, visual quantity badges,
  expiry warnings, confirmation dialogs
- Shopping List: gradient summary cards, aisle grouping with badges,
  sale strikethrough pricing, empty state
- Login: centered card with icon, Input component, Button component
- All old gray/blue utility classes migrated to new surface/primary tokens
- TypeScript clean, production build passes

frontend/package-lock.json

@@ -10,9 +10,14 @@
       "dependencies": {
         "@tanstack/react-query": "^5.17.0",
         "axios": "^1.6.5",
+        "clsx": "^2.1.1",
+        "framer-motion": "^12.38.0",
+        "lucide-react": "^1.16.0",
         "react": "^18.2.0",
         "react-dom": "^18.2.0",
-        "react-router-dom": "^6.21.1"
+        "react-hot-toast": "^2.6.0",
+        "react-router-dom": "^6.21.1",
+        "tailwind-merge": "^3.6.0"
       },
       "devDependencies": {
         "@types/react": "^18.2.48",
@@ -1756,6 +1761,15 @@
         "node": ">= 6"
       }
     },
+    "node_modules/clsx": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/clsx/-/clsx-2.1.1.tgz",
+      "integrity": "sha512-eYm0QWBtUrBWZWG0d386OGAw16Z995PiOVo2B7bjWSbHedGl5e0ZWaq65kOGgUSNesEIDkB9ISbTg/JK9dhCZA==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/color-convert": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/color-convert/-/color-convert-2.0.1.tgz",
@@ -1844,7 +1858,6 @@
       "version": "3.2.3",
       "resolved": "https://registry.npmjs.org/csstype/-/csstype-3.2.3.tgz",
       "integrity": "sha512-z1HGKcYy2xA8AGQfwrn0PAy+PB7X/GSj3UVJW9qKyn43xWa+gl5nXmU4qqLMRzWVLFC8KusUX8T/0kCiOYpAIQ==",
-      "dev": true,
       "license": "MIT"
     },
     "node_modules/debug": {
@@ -2363,6 +2376,33 @@
         "url": "https://github.com/sponsors/rawify"
       }
     },
+    "node_modules/framer-motion": {
+      "version": "12.38.0",
+      "resolved": "https://registry.npmjs.org/framer-motion/-/framer-motion-12.38.0.tgz",
+      "integrity": "sha512-rFYkY/pigbcswl1XQSb7q424kSTQ8q6eAC+YUsSKooHQYuLdzdHjrt6uxUC+PRAO++q5IS7+TamgIw1AphxR+g==",
+      "license": "MIT",
+      "dependencies": {
+        "motion-dom": "^12.38.0",
+        "motion-utils": "^12.36.0",
+        "tslib": "^2.4.0"
+      },
+      "peerDependencies": {
+        "@emotion/is-prop-valid": "*",
+        "react": "^18.0.0 || ^19.0.0",
+        "react-dom": "^18.0.0 || ^19.0.0"
+      },
+      "peerDependenciesMeta": {
+        "@emotion/is-prop-valid": {
+          "optional": true
+        },
+        "react": {
+          "optional": true
+        },
+        "react-dom": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/fs.realpath": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
@@ -2492,6 +2532,15 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/goober": {
+      "version": "2.1.19",
+      "resolved": "https://registry.npmjs.org/goober/-/goober-2.1.19.tgz",
+      "integrity": "sha512-U7veizMqxyKlM58+Z5j2ngJBH/r9siDmxpvNxSw0PylF6WQvrASJEZrxh1hidRBJc2jqoBVSyOban5u8m+6Rxg==",
+      "license": "MIT",
+      "peerDependencies": {
+        "csstype": "^3.0.10"
+      }
+    },
     "node_modules/gopd": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/gopd/-/gopd-1.2.0.tgz",
@@ -2860,6 +2909,15 @@
         "yallist": "^3.0.2"
       }
     },
+    "node_modules/lucide-react": {
+      "version": "1.16.0",
+      "resolved": "https://registry.npmjs.org/lucide-react/-/lucide-react-1.16.0.tgz",
+      "integrity": "sha512-dYwyPzb4MEKpGUmNYk3WKWPnMrHs3FKM+q94kAnJrcDIqqn1hq2xY8scaS2ovsOCM5D51ey2gaRG3PBb1vgoYQ==",
+      "license": "ISC",
+      "peerDependencies": {
+        "react": "^16.5.1 || ^17.0.0 || ^18.0.0 || ^19.0.0"
+      }
+    },
     "node_modules/math-intrinsics": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/math-intrinsics/-/math-intrinsics-1.1.0.tgz",
@@ -2927,6 +2985,21 @@
         "node": "*"
       }
     },
+    "node_modules/motion-dom": {
+      "version": "12.38.0",
+      "resolved": "https://registry.npmjs.org/motion-dom/-/motion-dom-12.38.0.tgz",
+      "integrity": "sha512-pdkHLD8QYRp8VfiNLb8xIBJis1byQ9gPT3Jnh2jqfFtAsWUA3dEepDlsWe/xMpO8McV+VdpKVcp+E+TGJEtOoA==",
+      "license": "MIT",
+      "dependencies": {
+        "motion-utils": "^12.36.0"
+      }
+    },
+    "node_modules/motion-utils": {
+      "version": "12.36.0",
+      "resolved": "https://registry.npmjs.org/motion-utils/-/motion-utils-12.36.0.tgz",
+      "integrity": "sha512-eHWisygbiwVvf6PZ1vhaHCLamvkSbPIeAYxWUuL3a2PD/TROgE7FvfHWTIH4vMl798QLfMw15nRqIaRDXTlYRg==",
+      "license": "MIT"
+    },
     "node_modules/ms": {
       "version": "2.1.3",
       "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.3.tgz",
@@ -3397,6 +3470,23 @@
         "react": "^18.3.1"
       }
     },
+    "node_modules/react-hot-toast": {
+      "version": "2.6.0",
+      "resolved": "https://registry.npmjs.org/react-hot-toast/-/react-hot-toast-2.6.0.tgz",
+      "integrity": "sha512-bH+2EBMZ4sdyou/DPrfgIouFpcRLCJ+HoCA32UoAYHn6T3Ur5yfcDCeSr5mwldl6pFOsiocmrXMuoCJ1vV8bWg==",
+      "license": "MIT",
+      "dependencies": {
+        "csstype": "^3.1.3",
+        "goober": "^2.1.16"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "peerDependencies": {
+        "react": ">=16",
+        "react-dom": ">=16"
+      }
+    },
     "node_modules/react-refresh": {
       "version": "0.17.0",
       "resolved": "https://registry.npmjs.org/react-refresh/-/react-refresh-0.17.0.tgz",
@@ -3718,6 +3808,16 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/tailwind-merge": {
+      "version": "3.6.0",
+      "resolved": "https://registry.npmjs.org/tailwind-merge/-/tailwind-merge-3.6.0.tgz",
+      "integrity": "sha512-uxL7qAVQriqRQPAyK3pj66VqskWqoZ37PW94jwOTwNfq/z9oyu1V+eqrZqtR2+fCiXdYOZe/Modt8GtvqNzu+w==",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/dcastil"
+      }
+    },
     "node_modules/tailwindcss": {
       "version": "3.4.19",
       "resolved": "https://registry.npmjs.org/tailwindcss/-/tailwindcss-3.4.19.tgz",
@@ -3854,6 +3954,12 @@
       "dev": true,
       "license": "Apache-2.0"
     },
+    "node_modules/tslib": {
+      "version": "2.8.1",
+      "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
+      "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
+      "license": "0BSD"
+    },
     "node_modules/type-check": {
       "version": "0.4.0",
       "resolved": "https://registry.npmjs.org/type-check/-/type-check-0.4.0.tgz",