Initialize or reopen storage and ensure buckets exist

Usage: mikrio init [OPTIONS] <DIR>

Arguments:
  <DIR>  Managed store directory

Options:
      --json             Emit schema 1 JSON results and diagnostics
      --region <REGION>  Signing region (mikrio_region; persisted value or us-east-1)
      --bucket <NAME>    Ensure this bucket exists; repeatable, preserves existing configuration
  -h, --help             Print help
