docs: add IDE Skills section to quickstart guide

Author: os-zhuang

content/docs/quickstart.mdx

@@ -81,6 +81,11 @@ REST endpoints, Studio views, audit log entries, permission gates.
 No file edited, no restart. See [Build → AI Builder](/docs/build/ai-builder)
 for the full vocabulary.
 
+> **Hand-coding in your IDE?** Run `npx skills add objectstack-ai/framework`
+> to teach Claude Code / Cursor / Copilot / Codex how to author
+> ObjectOS metadata against the real Zod schemas. See
+> [Build → IDE Skills](/docs/build/ai-skills).
+
 ### Install an app from the marketplace
 
 Open **http://localhost:3000/_studio/**, sign in, and pick an app: