chore: add changeset for quick-ref enhancement

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: himerus

.changeset/enhance-quick-ref.md

@@ -0,0 +1,6 @@
+---
+'helixir': patch
+'@helixir/core': patch
+---
+
+fix: quick-ref CSS snippet uses meaningful values instead of misleading 'initial', adds slot styling guidance