introduce workspace

crates/core/build.rs

@@ -0,0 +1,10 @@
+use std::process::Command;
+
+fn main() {
+    let output = Command::new("git")
+        .args(["rev-parse", "--short", "HEAD"])
+        .output()
+        .unwrap();
+    let git_hash = String::from_utf8(output.stdout).unwrap();
+    println!("cargo:rustc-env=GIT_HASH={git_hash}");
+}