chore(changeset): declare Metadata-protocol added and grade @objectstack/spec minor, as the level gate reads the moved authorable-surface shard

Claude-Session: https://claude.ai/code/session_01ADHkmPi3pqv7Vkx4kymD87
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

.changeset/29373-export-withheld-maps.md

@@ -1,11 +1,11 @@
 ---
-'@objectstack/spec': patch
+'@objectstack/spec': minor
 ---
 
 feat(spec): the package export manifest declares `withheldMaps`, the maps it withheld whole, and an unmanaged import accepts it
 
 Clause-②: yes (widening)
-Metadata-protocol: none
+Metadata-protocol: added
 
 `GET /packages/:id/export` writes each item as a served read returns it, so a connector's header and environment-variable maps are already withheld whole by the connector redactor and the exported item simply lacks them. An import elsewhere could not tell such a map from one the package never had. The export contract now has a place to say so: