Allow individual permission overrides alongside Teammate Groups

Problem
Since the permissions update removed individual-level access controls, admins must create a dedicated Teammate Group for every edge case where a single user needs a specific permission (e.g., View Analytics). This leads to a growing list of niche single-member groups that are hard to manage.

Request
Allow admins to grant permission overrides at the individual teammate level, even when Teammate Groups are the primary permission mechanism.