chore: grade metadata-core minor for its new anonymous-intake exports

The shared rule widens @objectstack/metadata-core's public index by five
exported symbols, which takes at least minor (Clause-② yes, widening).

Claude-Session: https://claude.ai/code/session_018zT8d8NpiQ1ExhuNd5TxY6
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

.changeset/public-form-withdrawal-one-rule.md

@@ -1,5 +1,5 @@
 ---
-'@objectstack/metadata-core': patch
+'@objectstack/metadata-core': minor
 '@objectstack/metadata-protocol': patch
 '@objectstack/rest': patch
 ---