feat(marketing-pages): subscribe to auth.user.signed-up

Generated handler + Payload event-task via gen event consume,
threaded through symbols / both binders / cms re-export at the
configured anchors. bus.subscribe wires the in-memory delivery in
dev-seed; the __events.auth.user.signed-up.marketing-pages Payload
task closes the production-bus loop.

Also fixes two generator-level issues found during Phase 8:
- Drop publisher prompt's `when` clause so --args can supply the
  4th positional argument (Plop limitation: --args cannot bypass
  conditional prompts). Validate runs only in consume mode.
- Switch event-task.ts.hbs from TaskConfig<"slug-string"> to
  TaskConfig<{ input: ...; output: object }> since runtime-generated
  event slugs are not keys of TypedJobs['tasks'].

packages/marketing-pages/src/di/bind-production.ts

@@ -16,6 +16,8 @@ import { getSiteSettingsUseCase } from "../application/use-cases/get-site-settin
 import { getPageBySlugUseCase } from "../application/use-cases/get-page-by-slug.use-case";
 import { getSiteSettingsController } from "../interface-adapters/controllers/get-site-settings.controller";
 import { getPageBySlugController } from "../interface-adapters/controllers/get-page-by-slug.controller";
+import { userSignedUpEvent } from "@repo/auth";
+import { onAuthUserSignedUpHandler } from "../events/handlers/on-auth-user-signed-up.handler";
 
 export function bindProductionMarketingPages(
   config: SanitizedConfig,
@@ -122,5 +124,24 @@ export function bindProductionMarketingPages(
   void bus;
   void queue;
   // <gen:event-handlers>
+  // onAuthUserSignedUpHandler subscription — generated, edit the handler file (not this block) for behavior.
+  const wrappedAuthUserSignedUp = withSpan(
+    tracer,
+    { name: "marketing-pages.onAuthUserSignedUpHandler", op: "event-handler" },
+    withCapture(
+      logger,
+      {
+        feature: "marketing-pages",
+        layer: "event-handler",
+        name: "marketing-pages.onAuthUserSignedUpHandler",
+      },
+      onAuthUserSignedUpHandler(),
+    ),
+  );
+  if (marketingPagesContainer.isBound(MARKETING_PAGES_SYMBOLS.IOnAuthUserSignedUpHandler)) {
+    marketingPagesContainer.unbind(MARKETING_PAGES_SYMBOLS.IOnAuthUserSignedUpHandler);
+  }
+  marketingPagesContainer.bind(MARKETING_PAGES_SYMBOLS.IOnAuthUserSignedUpHandler).toConstantValue(wrappedAuthUserSignedUp);
+  bus.subscribe(userSignedUpEvent, "marketing-pages", wrappedAuthUserSignedUp);
   // <gen:jobs>
 }