chore(web): redirect unauthenticated users to signin in checkout page

web/app/(app)/checkout/[planName]/page.tsx

@@ -2,12 +2,16 @@
 
 import { useState, useEffect } from 'react'
 import httpBrowserClient from '@/lib/httpBrowserClient'
+import { useSession } from 'next-auth/react'
+import { redirect } from 'next/navigation'
 
 export default function CheckoutPage({ params }) {
   const [error, setError] = useState<string | null>(null)
 
   const planName = params.planName as string
 
+  const { data: session } = useSession()
+
   useEffect(() => {
     const initiateCheckout = async () => {
       try {
@@ -25,6 +29,10 @@ export default function CheckoutPage({ params }) {
     initiateCheckout()
   }, [planName])
 
+  if (!session?.user) {
+    return redirect(`/login?redirect=${window.location.href}`)
+  }
+
   if (error) {
     return <div className='text-red-500'>{error}</div>
   }