Track ESM-only migration for published packages

Summary

The build currently emits a tsdown warning recommending ESM over CommonJS for @openzeppelin/ui-dev-cli because the package intentionally publishes dual esm/cjs outputs.

This is not currently breaking the build, but it would be useful to evaluate whether the published packages in this repo can move to ESM-only output and remove legacy CommonJS packaging over time.

Context

During pnpm build, packages/dev-cli logs:

WARN  We recommend using the ESM format instead of CommonJS.

The CLI currently publishes both formats on purpose, and consumer .pnpmfile.cjs support remains a separate concern.

Goal

Audit the published packages in this monorepo and decide whether we should:

• keep dual esm/cjs output as-is,
• suppress/accept the warning as expected noise, or
• migrate some or all published packages to ESM-only output.

Notes

• Priority: low
• This should likely be treated as packaging cleanup / modernization work, not as a release blocker.
• If pursued, the work should include a consumer compatibility check before removing any require exports.

Start by running pnpm build and inspect the published package configuration, beginning with packages/dev-cli and its dual ESM/CommonJS outputs. Audit the other published packages and check consumer compatibility, including .pnpmfile.cjs; done means documenting whether to retain dual output, suppress the warning, or migrate packages to ESM-only.