Version 0.1.5 release

Release 0.1.5 focuses on CLI output formatting and version reporting.

Highlights

• open-data-products explain <document> --json now returns structured ODPS
  and ODPG JSON instead of embedding line-oriented explanations as JSON strings.
• ODPG explain JSON includes graph metadata, node and edge counts, node types,
  relationship types, and node references.
• ODPS explain JSON includes product metadata, component count, compliance
  level, production-readiness status, and data access state.
• open-data-products summary <document> now prints a compact human-readable
  metadata report by default.
• open-data-products summary <document> --json preserves the previous
  machine-readable summary payload.
• open-data-products --version and open-data-products -V report the
  installed SDK version.