Get usage summary

curl --request GET \
  --url https://app.usechar.ai/api/plan-tiers/usage \
  --header 'Authorization: Bearer <token>'

{
  "plan_id": "<string>",
  "plan_name": "<string>",
  "features": {
    "sso": true,
    "scim": true,
    "audit_logs": true,
    "custom_domains": true
  },
  "usage": {
    "seats": {
      "current": 0,
      "limit": 0
    },
    "end_users": {
      "current": 0,
      "limit": 0
    }
  }
}