fix(scheduled-task): enable worker by default and add WeChat preflight

Scheduled automations were saved but never executed because the worker
required an explicit env flag. Follow H5_REMINDER_WORKER_ENABLED when unset,
add WeChat preflight to write tasks deterministically, and surface worker
warnings on create.

Co-authored-by: Cursor <cursoragent@cursor.com>

scheduled-task-worker.mjs

@@ -82,7 +82,9 @@ export function startScheduledTaskWorker({
             timeoutMs: executionTimeoutMs,
             logger,
           });
-          if (looksLikeScheduledTaskNonDelivery(result.deliveryText)) {
+          if (looksLikeScheduledTaskNonDelivery(result.deliveryText, {
+            readyPaths: result.readyPaths,
+          })) {
             const err = new Error('定时任务未产出可交付结果');
             err.code = 'SCHEDULED_TASK_NON_DELIVERY';
             throw err;