curl --request GET \
  --url https://api.faces.sh/v1/billing/llm-costs

[
  {
    "llm_model": "<string>",
    "provider": "<string>",
    "input_cost_per_million": 123,
    "output_cost_per_million": 123,
    "user_input_tokens": 123,
    "user_output_tokens": 123,
    "user_total_cost_usd": 123,
    "user_request_count": 123,
    "billing_unit": "<string>",
    "unit_cost_usd": 123,
    "billing_applies_to": "<string>"
  }
]