Introspect OAuth2 token

curl --request POST \
  --url https://api.fluxer.app/v1/oauth2/introspect \
  --header 'Content-Type: multipart/form-data' \
  --form 'token=<string>' \
  --form 'client_id=<string>' \
  --form 'client_secret=<string>'

{
  "active": true,
  "scope": "<string>",
  "client_id": "<string>",
  "username": "<string>",
  "token_type": "<string>",
  "exp": 1073741823,
  "iat": 1073741823,
  "sub": "<string>"
}