group_blobs_api mirrors the per-app kv_api/files_api for groups: GET
/groups/{id}/kv[/{c}/{k}], /docs[/{c}/{id}], /files[/{c}/{id}] — list +
fetch/download a group's §11.6 shared KV/docs/files. Authz GroupKvRead/
GroupDocsRead/GroupFilesRead (viewer tier, reads-open trust model). Read-only
by design (writes stay script-only). The host hoists the three group repos so
the SDK services and this router share one instance.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>