luna-jit vs luna-core vs luna-jit-helpers

A Lua runtime in pure Rust — full 5.1/5.2/5.3/5.4/5.5 support. Equivalent to `luna-core` plus a Cranelift-backed JIT (method + trace) and the lua.h-compatible C ABI. (The `luna` crate name on crates.io is taken by an unrelated utility library; this crate is the JIT-equipped variant of the goliajp/luna Lua runtime.)

Pure-Rust Lua runtime (interpreter only, zero third-party dependencies). The JIT-equipped variant lives in the `luna-jit` crate.

Shared `luna_jit_*` extern-C runtime helpers + per-thread JIT_VM/JIT_CL TLS slots + `enter_jit` RAII rebind for the goliajp/luna Lua runtime. Used by both `luna-jit` (Cranelift backend) and `luna-jit-llvm` (LLVM alt backend) so the helper symbol table and TLS discipline stay single-source-of-truth across JIT backends. Internal infrastructure crate — embedders should depend on `luna-jit`, not this crate directly.