fix: free tier shows payment form only after account created (auth-badge reveal)

src/checkout.el

@@ -136,7 +136,7 @@ fn checkout_page(plan: String, pub_key: String) -> String {
       </div>
 
       <!-- Payment form (visible immediately - no auth wall) -->
-      <div id=\"payment-section\">
+      <div id=\"payment-section\" " + (if is_free { "style=\"display:none;\"" } else { "" }) + ">
         <div id=\"auth-badge\" style=\"display:none; margin-bottom: 1.5rem;\"></div>
         " + (if is_free { "" } else { "
         <p class=\"checkout-auth-hint\" id=\"signin-prompt\" style=\"margin-bottom:1.25rem;font-size:.8125rem\">Already have an account? <a href=\"#\" onclick=\"document.getElementById('auth-section').style.display='';this.parentNode.style.display='none';return false;\" style=\"color:var(--navy);text-decoration:underline\">Sign in</a> to link your purchase.</p>
@@ -488,5 +488,23 @@ fn checkout_page(plan: String, pub_key: String) -> String {
 <script src=\"/assets/js/db455e1671dd.js\" defer></script>
 
 <script>window.NEURON_CFG=window.NEURON_CFG||{};window.NEURON_CFG.plan=\"" + plan + "\";window.NEURON_CFG.pub_key=\"" + pub_key + "\";</script><script src=\"/assets/js/e708dcbb3e7a.js\" defer></script>
+
+" + (if is_free { "
+<script>
+(function(){
+  // Free tier: reveal payment section only after the user has created / signed in.
+  // The existing checkout JS sets auth-badge visible on successful auth — watch for that.
+  var pay = document.getElementById('payment-section');
+  if (!pay) return;
+  var timer = setInterval(function(){
+    var badge = document.getElementById('auth-badge');
+    if (badge && badge.offsetParent !== null) {
+      pay.style.display = '';
+      clearInterval(timer);
+    }
+  }, 150);
+})();
+</script>
+" } else { "" }) + "
 "
 }