Select Default Organization and Coaching Relationship

[jhodapp]

Description:
As a coach or coachee, I want the system to automatically select my default organization and coaching relationship, so that I can quickly access the relevant coaching session details.

Definition of Done:

• I want an API endpoint to return the user's default organization
• For each user, the system selects the first organization they are associated with as their default organization
• I want an API endpoint to return the user's default coaching relationship
• For each user, the system selects the first coaching relationship linked to another user (coach or coachee) as their default coaching relationship