chore(changeset): declare Clause-② yes (narrowing) for the checkPageSlotPair export

The diff exports checkPageSlotPair from the spec ui entry, a public-surface
widening beside the accept-set narrowing; widen-plus-narrow is spelled
yes (narrowing). Levels unchanged (spec minor, platform-objects patch).

Claude-Session: https://claude.ai/code/session_01VZqqwTj2wsihZEbfT6yyYN
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

.changeset/22568-page-slots-details-beside-tabs-refused.md

@@ -5,7 +5,7 @@
 
 feat(spec)!: `PageSchema` refuses a page that authors both `slots.details` and `slots.tabs`; the `sys_user` record page carries its details grid as its first tab
 
-Clause-②: no (narrowing)
+Clause-②: yes (narrowing)
 
 <!-- adr-0087: registered page-slots-details-beside-tabs-refused -->