curl -X POST 'https://api.example.com/tag-assignments' \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{
    "tagId": "tag_engineering",
    "targetType": "subject",
    "targetId": "subject_jane",
    "scopeId": "scope_acme"
  }'

{
  "id": "tag_assignment_0190a1b2-c3d4-7e5f-8a9b-0c1d2e3f4a5b",
  "tagId": "tag_engineering",
  "targetType": "subject",
  "targetId": "subject_jane",
  "scopeId": "scope_acme",
  "appliedBy": "subject_admin",
  "appliedAt": "2024-01-15T10:30:00Z"
}