Implement Save Shared Duties API in Mobile App with FHIR Compliance

[dunexploration-react]

Feature Description
Implement the Save Shared Duties API to allow users to create and assign pet care duties that can be shared with other users linked to the same pet.

Describe the solution you'd like
This API will save shared duty records with fields such as duty type (e.g., Feeding, Walking), description, assigned user, schedule, and status. It enables users to effectively coordinate shared responsibilities for pet care through the mobile app, with data formatted according to FHIR standards.