fix: free checkout requires Stripe SetupIntent for age verification; update copy

src/main.el

@@ -637,7 +637,7 @@ fn handle_request_inner(method: String, path: String, headers: Map, body: String
             "Secure your Founding Member spot. Pay once, $199 lifetime — Neuron inference included at launch, priced below the major APIs. First 1,000 only."
         } else {
             if str_eq(plan, "free") {
-                "Create your free Neuron account. No credit card required. Your AI that remembers you — runs on your machine, never resets."
+                "Create your free Neuron account. A card verifies you're 18+ — you won't be charged. Your AI that remembers you, runs on your machine, never resets."
             } else {
                 "Subscribe to Neuron Professional for $19/month. The AI that remembers you — persistent memory, runs locally, bring your own API keys."
             }