Add settings page with profile, billing, notifications, security tabs

- Create comprehensive settings page with 4 tabs
- Profile: name editing with save functionality
- Billing: subscription display with Stripe portal link
- Notifications: toggle switches for email preferences
- Security: password change, 2FA placeholder, account deletion
- Add shadcn Switch component

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -15,13 +15,16 @@
     "@radix-ui/react-label": "^2.1.8",
     "@radix-ui/react-separator": "^1.1.8",
     "@radix-ui/react-slot": "^1.2.4",
+    "@radix-ui/react-switch": "^1.2.6",
     "@radix-ui/react-tabs": "^1.1.13",
     "@stripe/stripe-js": "^8.5.3",
     "@supabase/ssr": "^0.8.0",
     "@supabase/supabase-js": "^2.87.1",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
+    "date-fns": "^4.1.0",
     "lucide-react": "^0.561.0",
+    "motion": "^12.23.26",
     "next": "16.0.10",
     "next-themes": "^0.4.6",
     "react": "19.2.1",