Add freemium variant C: archetype persistence, dashboard banner, lesson gate

- User.archetype/utmSource/utmMedium/utmCampaign fields + migration
- register flow reads ?archetype/?utm_* and saves them on the User row
- dashboard ArchetypeBanner: per-archetype 'твой путь' block
- lesson gate after wow-moment lesson (WOW_MOMENT_LESSON_ID=obs-start-l2-006) → tripwire + full-course offer

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/(auth)/register/page.tsx

@@ -2,13 +2,20 @@ import { redirect } from "next/navigation";
 import { getSettings } from "@/lib/settings";
 import { RegisterForm } from "./register-form";
 
-export default async function RegisterPage() {
+export default async function RegisterPage({
+  searchParams,
+}: {
+  searchParams: Promise<{ [key: string]: string | string[] | undefined }>;
+}) {
   const settings = await getSettings();
 
   if (settings.registrationEnabled !== "true") {
     redirect("/login?notice=registration_closed");
   }
 
+  const sp = await searchParams;
+  const str = (v: string | string[] | undefined) => (Array.isArray(v) ? v[0] : v) ?? "";
+
   return (
     <div className="min-h-screen flex items-center justify-center" style={{ backgroundColor: "var(--background)" }}>
       <div className="w-full max-w-sm">
@@ -26,6 +33,10 @@ export default async function RegisterPage() {
             privacyPolicyUrl={settings.privacyPolicyUrl}
             termsUrl={settings.termsUrl}
             offerUrl={settings.offerUrl}
+            archetype={str(sp.archetype)}
+            utmSource={str(sp.utm_source)}
+            utmMedium={str(sp.utm_medium)}
+            utmCampaign={str(sp.utm_campaign)}
           />
         </div>
       </div>