// Package providers holds the concrete CloudAdapter implementations behind the
// provision.AdapterFactory boundary (doc/04 §4: "厂商 API 适配层").
//
// First launch ships two vendors — one per pool (doc/04 §5.2):
//
//   - vultr   — consumable pool (entry/free): cheap, hourly-billed small vendor.
//   - hetzner — premium pool (exit / pro entry): stable, good native IPs.
//
// CREDENTIAL RED LINE (doc/06 §2): adapters read their API credentials ONLY
// from independent secrets (environment variables here). Credentials are never
// stored in the providers table, never logged, and never committed to git. The
// Registry binds providers.api_kind → adapter at wiring time.
//
// Identity isolation: each vendor MUST use a fully independent account / email /
// crypto payment, registered in infra/identity-isolation.md.
package providers