web: newsletter signup on download page

web/app/download/signup.tsx

@@ -0,0 +1,46 @@
+'use client'
+
+import { useState } from 'react'
+
+export default function () {
+  const [email, setEmail] = useState('')
+  const [success, setSuccess] = useState(false)
+
+  return (
+    <form
+      onSubmit={async e => {
+        e.preventDefault()
+
+        await fetch('/api/signup', {
+          method: 'POST',
+          headers: {
+            'Content-Type': 'application/json',
+          },
+          body: JSON.stringify({ email }),
+        })
+
+        setSuccess(true)
+        setEmail('')
+
+        return false
+      }}
+      className='flex self-stretch flex-col gap-3 h-32'
+    >
+      <input
+        required
+        autoFocus
+        value={email}
+        onChange={e => setEmail(e.target.value)}
+        type='email'
+        placeholder='your@email.com'
+        className='bg-neutral-100 rounded-lg px-4 py-2 focus:outline-none placeholder-neutral-500'
+      />
+      <input
+        type='submit'
+        value='Get updates'
+        className='bg-black text-white rounded-lg px-4 py-2 focus:outline-none cursor-pointer'
+      />
+      {success && <p className='text-center text-sm'>You&apos;re signed up for updates</p>}
+    </form>
+  )
+}