<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **New Features**
* Added a mutation to request/apply a subscription by transaction ID
(client mutation and server operation), returning subscription details.
* **Bug Fixes / Improvements**
* More robust external subscription sync with safer conflict detection,
optional short-lived confirmation, improved parsing and error logging.
* **Chores**
* Standardized time constants for clarity.
* **Tests**
* Updated subscription test data (expiration date) to reflect new
lifecycle expectations.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
DarkSky