v1.10.1 Patchfix: add to_json and protect device_mesh import

AI Impact Summary

v1.10.1 adds a new to_json serialization helper and implements import protection for the device_mesh module, addressing prior import-time errors and serialization gaps. This enables downstream services to serialize objects reliably and prevents crashes when device_mesh is not present in the deployment environment. The changes, contributed by @S1ro1 (#3743) and @SunMarc (#3742), focus on capability enhancements without introducing breaking changes.