MIF v1.3.0

Added

• Container Profile (ADR-021) — an OPTIONAL, single-file *.corpus.json
  transport envelope that serializes a Bundle (or a subset of one) for wire
  transport: schema/container.schema.json, schema/container-context.jsonld,
  schema/document-reference.schema.json, scripts/validate_container.py,
  a container-validation CI job, a worked example under
  examples/container/, and docs/CONTAINER-PROFILE.md. Vendor-specific
  corpus metadata (compression manifests, version DAGs) routes through a
  generalized extensions mechanism rather than becoming native MIF
  vocabulary. Accepted and implemented in the same change (reframes
  issue #77).
• [Tooling]: scripts/check_relationship_type_vocab_coverage.py — cross-checks
  schema/context.jsonld's relationships.type.@context term mapping against
  public/ns/vocabulary.jsonld's registered rdfs:Class terms, guarding against
  the #230 defect class (a relationship-type term declared in one file but never
  wired to the other) recurring. Wired into the okf-conformance CI job. (#233)
• [Tooling]: scripts/test_temporal_and_properties.py (temporal-consistency
  and properties-construct regression suite) is now run in the okf-conformance
  CI job via pytest; previously it only ran if a contributor had pytest
  installed locally and remembered to invoke it by hand. (#235)