feat(marketing-pages): sendWelcomeEmail job + handler enqueues it

sendWelcomeEmailJob takes IMailerService, validates the typed input
(userId + email), and delegates to mailer.sendWelcome. The
onAuthUserSignedUpHandler now takes IJobQueue and enqueues
"marketing-pages.send-welcome-email" with the event payload.

Both binders bind a RecordingMailerService at the IMailerService
symbol (production placeholder until a real adapter ships) and pass
mailer / queue into the wrapped factories. Dev-seed additionally
queue.register()s the slug so the in-memory queue dispatches via
the wrapped job; production relies on the generated Payload event-task
to resolve the wrapped handler from the container.

packages/marketing-pages/src/integrations/cms/index.ts

@@ -1,4 +1,5 @@
 export { pages } from "./collections/pages";
 export { siteSettings } from "./globals/site-settings";
 // <gen:job-tasks>
+export { sendWelcomeEmailTask } from "./jobs/send-welcome-email.task";
 export { onAuthUserSignedUpEventTask } from "./jobs/__events-auth-user-signed-up.task";

packages/marketing-pages/src/integrations/cms/jobs/send-welcome-email.task.ts

@@ -0,0 +1,18 @@
+// packages/marketing-pages/src/integrations/cms/jobs/send-welcome-email.task.ts
+import type { TaskConfig } from "payload";
+import { marketingPagesContainer } from "../../../di/container";
+import { MARKETING_PAGES_SYMBOLS } from "../../../di/symbols";
+import type { ISendWelcomeEmailJob } from "../../../jobs/send-welcome-email.job";
+
+export const sendWelcomeEmailTask: TaskConfig<"marketing-pages.send-welcome-email"> = {
+  slug: "marketing-pages.send-welcome-email",
+  inputSchema: [],
+  retries: { attempts: 3, backoff: { type: "exponential", delay: 1000 } },
+  handler: async ({ input }) => {
+    const job = marketingPagesContainer.get<ISendWelcomeEmailJob>(
+      MARKETING_PAGES_SYMBOLS.ISendWelcomeEmailJob,
+    );
+    await job(input as never);
+    return { output: {} };
+  },
+};