v0.6.1

The <Concluding> status release. A <Concluding> may now carry an
optional status attribute recording the terminal disposition of the
Goal it closes, aligning the reference parser/validator with the ratified
v0.6.1 spec contract.

• <Concluding status=...> — status is an optional enum
  (met|unmet|partially_met) on the Concluding dataclass and in
  KIND_SPECIFIC_FIELDS['Concluding']. The parser accepts it, the
  serializer round-trips it, and compute_canonical_id folds it into the
  content hash only when present. A status-less <Concluding> parses and
  validates exactly as before (v0.5/v0.6.0 back-compat).
• Validator — when status is present it must be one of
  met|unmet|partially_met; an out-of-enum value is a hard validation
  error (under the v031_optional_fields rule). The goal_declared rule
  now reads Concluding.status: a required Goal is closed by a status-less
  Concluding (back-compat) or one carrying an in-enum status.
• Versions — the package version (pyproject + __version__) and
  SCHOLIA_VALIDATOR_VERSION both move to 0.6.1. The registry format
  version stays 0.6 (it tracks the on-disk format, not the patch).
• Publish hygiene — internal references were scrubbed from src/,
  tests/, and fixtures, and a CI leak guard
  (tests/unit/scholia/test_public_hygiene.py) now hard-fails on the
  forbidden token set across src/, tests/, and scripts/.
• Registry DAG naming — the registry's in-memory return type is now
  VerificationDag (a content-addressed DAG of verification relationships,
  not a linear chain), surfaced via walk_dag / to_verification_dag /
  dag_to_dict / dag_from_dict and backed by the
  scholialang.verification_dag shim. The default on-disk registry path
  becomes ~/.scholia/registry.verification_dag.json. This settles the
  interim v0.6.0 DAG-shape naming before the v0.6.1 publish, so the
  registry's public surface debuts under the accurate verification_dag
  name rather than the inaccurate "chain" framing.