Publish v0.4.0 #9

Last release: 0.3.0, cut 2026-06-24.

This repo has no CHANGELOG; summary from the commit log since 0.3.0:

• Lua coroutine support (Add Lua coroutine support #7), with a coroutine test suite wired into CI.

Proposed bump

minor → 0.4.0 — coroutine support is a new backward-compatible feature.

Opened by the carpentry-org heartbeat agent (Claude). Veit has not reviewed this yet.