feat(cron): add --account flag for multi-account delivery routing (#26284)

* feat(cron): add --account flag for multi-account delivery routing

Add support for explicit delivery account routing in cron jobs across CLI, normalization, delivery planning, and isolated delivery target resolution.

Highlights:
- Add --account <id> to cron add and cron edit
- Add optional delivery.accountId to cron types and delivery plan
- Normalize and trim delivery.accountId in cron create/update normalization
- Prefer explicit accountId over session lastAccountId and bindings fallback
- Thread accountId through isolated cron run delivery resolution
- Preserve cron edit --best-effort-deliver/--no-best-effort-deliver behavior by keeping implicit announce mode
- Expand tests for account passthrough/merge/precedence and CLI account flows

* cron: resolve rebase duplicate accountId fields

---------

Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/cron/delivery.ts

@@ -4,6 +4,7 @@ export type CronDeliveryPlan = {
   mode: CronDeliveryMode;
   channel?: CronMessageChannel;
   to?: string;
+  /** Explicit channel account id from the delivery config, if set. */
   accountId?: string;
   source: "delivery" | "payload";
   requested: boolean;
@@ -59,12 +60,11 @@ export function resolveCronDeliveryPlan(job: CronJob): CronDeliveryPlan {
     (delivery as { channel?: unknown } | undefined)?.channel,
   );
   const deliveryTo = normalizeTo((delivery as { to?: unknown } | undefined)?.to);
+  const channel = deliveryChannel ?? payloadChannel ?? "last";
+  const to = deliveryTo ?? payloadTo;
   const deliveryAccountId = normalizeAccountId(
     (delivery as { accountId?: unknown } | undefined)?.accountId,
   );
-
-  const channel = deliveryChannel ?? payloadChannel ?? "last";
-  const to = deliveryTo ?? payloadTo;
   if (hasDelivery) {
     const resolvedMode = mode ?? "announce";
     return {