B2 Native API v3 client for the ACG B2 account: status, buckets, keys, files, bucket-size, usage/cost ($0.00695/GB), gated create/delete bucket+key, and gated lifecycle-based delete-prefix/lifecycle-remove for prefix purges. Read-only by default; destructive ops require --confirm. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>