Returns the branch the calling user is assigned to. Available to Head Branch Managers, Branch Managers, and Advisors only.

Root Advisors cannot use this endpoint — they are not assigned to any specific branch (they manage all branches). Root Advisors should use GET /branches/private/v1/branch to list all branches or GET /branches/private/v1/branch/{branchId} to get a specific branch. Calling this endpoint as Root Advisor returns RELATION_NOT_FOUND.