feat(openshell): inventory explicitly selected policy documents

[pengfei-threemoonslab]

A reviewer can now register arbitrary repository-local OpenShell YAML/JSON policies in .shipgate/openshell.json and inspect their typed authority facts with shipgate audit --host. The reader pins OpenShell 0.1.2 separately from policy schema 1, preserves authored/effective-snapshot roles and default provenance, and names missing, malformed, unsupported, or escaping inputs as blocking coverage limits.

Network facts retain binary/endpoint correlation. Parsing is bounded, identity-bound and offline; credential-shaped labels cannot silently collapse under redaction. New host inventory/baseline/drift v0.8 schemas leave historical schemas frozen. Discovery, the zero-install launcher, independent census, generated references and a sample are included.

Semantic comparison, Git-selected input binding, review routing, composition and optional native proof follow in #944–#948. This stage makes no deployed enforcement or tool-effect claim.

Validation: full suite exercised 14,979 cases (14,955 initially passed); all seven failing cases and twelve packaging errors passed in the corrected regression run with build-dependency network access. OpenShell fixtures, schema generation check, Ruff, diff whitespace check and self-check passed. Reviewed the implementation and addressed census/launcher discovery, coverage parity and generated-document gaps. check/verify now report review_publishable: publishing is allowed; human review of the new registration and trigger catalog is required before merge.

Closes #943
Part of #942