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'].
