curl --request POST \
  --url https://geoff.ai/api/v1/voice/upload-audio \
  --header 'Authorization: Bearer <token>' \
  --form 'file=@voice_sample.mp3' \
  --form 'purpose=voice-clone'

{
  "data": {
    "file_id": "file_abc123",
    "filename": "voice_sample.mp3",
    "duration": 15.4,
    "format": "mp3"
  }
}