chore: add empty changeset for docs-only skills update

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: os-zhuang

.changeset/docs-skills-install-and-generated.md

@@ -0,0 +1,7 @@
+---
+---
+
+docs(skills): document the skill install command and generate the skill catalog
+(README index + guide tables/cards) from each `SKILL.md` frontmatter via a new
+`build-skill-docs.ts` script. Documentation + dev-tooling only — no package
+runtime change, so this is an empty changeset.