Create a DigitalOcean Droplet via API with SSH keys attached, poll until active, and retrieve its public IPv4

Documented steps

1. Create a personal access token in the DigitalOcean control panel (cloud.digitalocean.com -> API -> Applications & API). Use custom scopes (e.g. droplet:create, droplet:read, ssh_key:read) or full write access. Send it as 'Authorization: Bearer $TOKEN' on every request.
2. Ensure the SSH key already exists in the account (GET https://api.digitalocean.com/v2/account/keys). The ssh_keys array accepts numeric key IDs and/or MD5 fingerprints.
3. POST https://api.digitalocean.com/v2/droplets with Content-Type: application/json. Required fields: name, region (slug e.g. 'nyc3'), size (slug e.g. 's-1vcpu-1gb'), image (slug e.g. an ubuntu slug, or an image/snapshot ID). Example body: {"name":"web-1","region":"nyc3","size":"s-1vcpu-1gb","image":"ubuntu-24-04-x64","ssh_keys":[289794,"3b:16:e4:..."]}. Optional: tags, user_data (cloud-init), monitoring, backups, vpc_uuid.
4. Creation is asynchronous: the response includes the droplet (status 'new') and a links.actions entry. Poll GET https://api.digitalocean.com/v2/droplets/{droplet_id}/actions/{action_id} every few seconds until action status is 'completed'.
5. Then GET https://api.digitalocean.com/v2/droplets/{droplet_id} and read networks.v4[]; the entry with type 'public' has the public IPv4 in ip_address. Confirm droplet.status is 'active'.
6. Valid region/size/image slugs are discoverable via GET /v2/regions, /v2/sizes, /v2/images. Docs: https://docs.digitalocean.com/reference/api/ and https://docs.digitalocean.com/products/droplets/how-to/create/