Pay-per-use vision model API

# macOS: replace "base64 -w0 street.webp" with "base64 -i street.webp"
curl https://api.stack.foldbun.com/v1/segment \
  -H "Authorization: Bearer $FOLDBUN_API_KEY" \
  -H "Content-Type: application/json" \
  -d @- <<EOF
{"model": "sam3", "image": {"base64": "$(base64 -w0 street.webp)"},
 "prompts": [{"text": "car"}, {"text": "person"}]}
EOF

import base64, os, requests

with open("street.webp", "rb") as f:
    image = base64.b64encode(f.read()).decode()

r = requests.post(
    "https://api.stack.foldbun.com/v1/segment",
    headers={"Authorization": f"Bearer {os.environ['FOLDBUN_API_KEY']}"},
    json={"model": "sam3",
          "image": {"base64": image},
          "prompts": [{"text": "car"}, {"text": "person"}]},
    timeout=60,
)
r.raise_for_status()
print(r.json())

{
  "id": "call_01a1913c-25a0-73fd-a074-7a6ac6154590",
  "model": "sam3",
  "image": {"height": 1008, "id": "img_312c4e3a…c6e2", "width": 1343},
  "cache": "miss",
  "imageFee": 0.5,
  "instances": [
    {
      "score": 0.9696,
      "bbox": [0, 716, 207, 889],
      "area": 27120,
      "prompt": 0,
      "label": "car",
      "polygon": [
        {"outer": [47, 718, 100, 728, 132, 743, …]}
      ]
    }
    … 26 more
  ],
  "dropStats": [],
  "cost": 0.6,
  "balance": 1233.96
}