[isomorphisms]

Adds a Kitchen-managed Lua 5.5.1 interpreter path.

• pins the official Lua 5.5.1 source archive and published SHA-256
• builds into an explicit prefix without root or a package manager
• installs versioned lua/luac executables and safe unversioned symlinks
• refuses unrelated existing lua/luac paths and corrupt archives
• adds a real Lua evaluation smoke test and GitHub Actions coverage
• records upstream provenance under sources/lua.md

The task follows Kitchen's requirements → test → numbered candidate structure.