Add ruby-rbs crate

This commit introduces the `ruby-rbs` crate, which will provide a safe,
high-level Rust API for the RBS C library. It follows the common Rust
pattern of separating the safe wrapper from the `*-sys` crate that
provides the raw FFI bindings.

The `ruby-rbs` crate will depend on `ruby-rbs-sys` for the unsafe C
bindings and will expose a safe, idiomatic Rust interface. This commit
sets up the foundation for that structure.

The initial implementation includes:
- The basic crate structure with its own Cargo.toml, declaring a
  dependency on `ruby-rbs-sys`.
- A build script (`build.rs`) that will be responsible for generating
  safe Rust wrappers from the C API. Currently, it only generates an
  empty `bindings.rs` file.
- The `ruby-rbs` crate is added to the main workspace `Cargo.toml`.

While the interaction is not yet implemented, this setup paves the way
for providing a robust Rust interface for RBS, which will improve safety
and developer experience.

Author: alexcrocha

rust/Cargo.lock

@@ -1,5 +1,6 @@
 [workspace]
 members = [
+  "ruby-rbs",
   "ruby-rbs-sys",
 ]
 

rust/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "ruby-rbs"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+ruby-rbs-sys = { path = "../ruby-rbs-sys" }

rust/ruby-rbs/Cargo.toml

@@ -0,0 +1,25 @@
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::Path;
+
+fn main() {
+    println!("cargo:warning=Build script is running!");
+
+    if let Err(err) = generate() {
+        panic!("build.rs failed: {err}");
+    }
+}
+
+fn generate() -> Result<(), Box<dyn std::error::Error>> {
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let dest_path = Path::new(&out_dir).join("bindings.rs");
+
+    let mut file = File::create(&dest_path)?;
+
+    writeln!(file, "// Generated by build.rs")?;
+    writeln!(file, "// Do not edit this file directly")?;
+    writeln!(file, "")?;
+
+    Ok(())
+}

rust/ruby-rbs/build.rs

@@ -0,0 +1 @@
+