This crate builds the `rexlang-lsp` binary: a Language Server Protocol (LSP) implementation for Rex,
built on `tower-lsp`.
It’s designed to run over stdio (the usual editor integration path), and it powers the VS Code
extension in `rexlang-vscode/`.
```sh
cargo build -p rexlang-lsp
```
Most users don’t run this directly; editors spawn it. For debugging, you can run it under an LSP
client that speaks stdio.