Add crate for the Ethereum contracts

processor/ethereum/contracts/build.rs

@@ -0,0 +1,45 @@
+use std::process::Command;
+
+fn main() {
+  println!("cargo:rerun-if-changed=contracts/*");
+  println!("cargo:rerun-if-changed=artifacts/*");
+
+  for line in String::from_utf8(Command::new("solc").args(["--version"]).output().unwrap().stdout)
+    .unwrap()
+    .lines()
+  {
+    if let Some(version) = line.strip_prefix("Version: ") {
+      let version = version.split('+').next().unwrap();
+      assert_eq!(version, "0.8.25");
+    }
+  }
+
+  #[rustfmt::skip]
+  let args = [
+    "--base-path", ".",
+    "-o", "./artifacts", "--overwrite",
+    "--bin", "--abi",
+    "--via-ir", "--optimize",
+
+    "./contracts/IERC20.sol",
+
+    "./contracts/Schnorr.sol",
+    "./contracts/Deployer.sol",
+    "./contracts/Sandbox.sol",
+    "./contracts/Router.sol",
+
+    "./contracts/tests/Schnorr.sol",
+    "./contracts/tests/ERC20.sol",
+
+    "--no-color",
+  ];
+  let solc = Command::new("solc").args(args).output().unwrap();
+  assert!(solc.status.success());
+  let stderr = String::from_utf8(solc.stderr).unwrap();
+  for line in stderr.lines() {
+    if line.contains("Error:") {
+      println!("{stderr}");
+      panic!()
+    }
+  }
+}