refactor: consume custom block contracts from core

[naaiyy]

Summary

• import the portable custom-block definition, registry, node, and asset contracts from @openeditor/core
• retain @openeditor/custom-block only where React editor and viewer adapters are used
• remove the custom-block dependency from @baseblocks/openeditor-contracts
• align every BaseBlocks OpenEditor dependency to the lockstep 0.0.52 release

Verification

• bun run lint
• bun test — 301 passed
• bun turbo run check-types --cache=local:r — 0 cached, 7 passed
• bun turbo run build --cache=local:r — 0 cached, production build passed

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
base-blocks	Ready	Preview	Aug 30, 2026 9:58pm

[github-actions]

React Doctor found no new issues. 🎉

_{Reviewed by React Doctor for commit 3c56c67.}