Distinguish Technicians from Admins in TechsForCategory API endpoint

GET /api/TechsForCategory returns every admin, since admins can be assigned in any category, together with the technicians who actually have permission for that category, and nothing in the response tells the two apart. The category and group admin pages already show this (users marked "(admin)", direct technician permissions, and "(group)" rows), but the API only offers write calls such as AddCategoryTechPermission and AddUserToGroup, so the only way to build a reliable "categories this tech handles" list for automation or reporting is to scrape those pages. Please add an access-type field to each user in the response (for example "AccessType": "admin" | "direct" | "group", with GroupID when the access comes through a group), or add read endpoints for category permissions and group membership.