Adds Store.listMeta() and Store.listSchemas() to expose meta-schema
discovery, backed by an in-memory metaSet (memory store) and a
persistent _index/_meta file (FS store). Surfaces both via new
json-cas list-meta and list-schema CLI commands wrapped in
@output/list-meta and @output/list-schema envelope schemas.
The FS store migrates from existing nodes when _meta is absent
(scanning self-referencing nodes) and preserves _meta on subsequent
opens. delete() removes affected hashes from the meta index and
persists the change.
Closes#90
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
xiaoju
55144d0e4a