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'].

turbo/generators/templates/event/consume/event-task.ts.hbs

@@ -9,7 +9,10 @@ import { {{constantCase feature}}_SYMBOLS } from "../../../di/symbols";
 import type { IOn{{pascalCase publisher}}{{pascalCase event}}Handler } from "../../../events/handlers/on-{{kebabCase publisher}}-{{kebabCase event}}.handler";
 import type { {{pascalCase event}}Event } from "@repo/{{kebabCase publisher}}";
 
-export const on{{pascalCase publisher}}{{pascalCase event}}EventTask: TaskConfig<"__events.{{kebabCase publisher}}.{{event}}.{{kebabCase feature}}"> = {
+export const on{{pascalCase publisher}}{{pascalCase event}}EventTask: TaskConfig<{
+  input: {{pascalCase event}}Event;
+  output: object;
+}> = {
   slug: "__events.{{kebabCase publisher}}.{{event}}.{{kebabCase feature}}",
   inputSchema: [],
   retries: { attempts: 3, backoff: { type: "exponential", delay: 1000 } },
@@ -17,7 +20,7 @@ export const on{{pascalCase publisher}}{{pascalCase event}}EventTask: TaskConfig
     const handler = {{camelCase feature}}Container.get<IOn{{pascalCase publisher}}{{pascalCase event}}Handler>(
       {{constantCase feature}}_SYMBOLS.IOn{{pascalCase publisher}}{{pascalCase event}}Handler,
     );
-    await handler(input as {{pascalCase event}}Event);
+    await handler(input);
     return { output: {} };
   },
 };