implement free plan age verification via Stripe SetupIntent; personalize soul demo greeting with user name and timezone

src/checkout.el

@@ -79,7 +79,7 @@ fn checkout_page(plan: String, pub_key: String) -> String {
     let plan_desc: String = if is_founding {
         "Pay once. Neuron inference when it launches - priced below the major APIs. No subscription, ever."
     } else { if is_free {
-        "Start building your memory. No card required."
+        "Start building your memory. A card verifies you're 18+. You won't be charged."
     } else {
         "Full access. Bring your own API keys or use Neuron Inference when it launches - Q3 2026."
     } }
@@ -142,7 +142,7 @@ fn checkout_page(plan: String, pub_key: String) -> String {
 
     let auth_heading: String = if is_free {
         el_p("class=\"label\" style=\"margin-bottom: 1.5rem; color: var(--navy);\"", "Create your account.")
-        + el_p("class=\"checkout-auth-hint\" style=\"margin-bottom: 2rem;\"", "No card required. Your account is free, forever.")
+        + el_p("class=\"checkout-auth-hint\" style=\"margin-bottom: 2rem;\"", "Create your account. We'll ask for a card to verify your age - you won't be charged.")
     } else {
         el_p("class=\"label\" style=\"margin-bottom: 1.25rem;\"", "Sign in (optional)")
         + el_p("class=\"checkout-auth-hint\"", "Sign in to link this purchase to an existing account. Or skip and create one later - we'll match it to your email.")
@@ -201,15 +201,7 @@ fn checkout_page(plan: String, pub_key: String) -> String {
 
     // ── Free-tier success panel ───────────────────────────────────────────────
 
-    let free_success: String = if is_free {
-        el_div(
-            "id=\"free-success\" style=\"display:none; text-align:center; padding: 2.5rem 1rem;\"",
-            el_div("style=\"font-size:2.5rem; margin-bottom:1.25rem;\"", "✓")
-            + el_p("class=\"label\" style=\"margin-bottom:.75rem; color:var(--navy);\"", "You're in.")
-            + el_p("class=\"checkout-auth-hint\" style=\"margin-bottom:2rem;\"", "Your free account is ready. Download Neuron to get started.")
-            + el_a("/marketplace", "class=\"checkout-submit\" style=\"display:inline-block; text-decoration:none; padding:.875rem 2rem;\"", "Go to your account →")
-        )
-    } else { "" }
+    let free_success: String = ""
 
     // ── Payment section ───────────────────────────────────────────────────────
 
@@ -281,7 +273,7 @@ fn checkout_page(plan: String, pub_key: String) -> String {
         + "<path d=\"M4 7l1.5 1.5L8.5 5\" stroke=\"currentColor\" stroke-width=\"1.2\" stroke-linecap=\"round\" stroke-linejoin=\"round\"/>"
         + "</svg>"
 
-    let submit_label: String = if is_free { "Reserve free tier &#8594;" } else { "Complete purchase &#8594;" }
+    let submit_label: String = if is_free { "Verify age &amp; get started &#8594;" } else { "Complete purchase &#8594;" }
 
     let payment_form: String = el_form(
         "id=\"payment-form\" autocomplete=\"on\"",
@@ -347,9 +339,7 @@ fn checkout_page(plan: String, pub_key: String) -> String {
     let cfg_js: String = "window.NEURON_CFG=window.NEURON_CFG||{};window.NEURON_CFG.plan=\"" + plan + "\";window.NEURON_CFG.pub_key=\"" + pub_key + "\";"
     let cfg_script: String = el_script_inline(cfg_js)
     let stripe_el_script: String = el_script_src("/js/checkout-stripe.js", true)
-    let free_init_script: String = if is_free {
-        el_script_inline("document.addEventListener('DOMContentLoaded',function(){window.neuronCheckoutFree&&window.neuronCheckoutFree()});")
-    } else { "" }
+    let free_init_script: String = ""
 
     return nav_html + main_html + supabase_script + stripe_script + style_html + auth_script + cfg_script + stripe_el_script + free_init_script
 }