Improve packaging (#328)

* Add gpgui-helper (#326)

* Add packaging

crates/gpapi/src/utils/checksum.rs

@@ -0,0 +1,14 @@
+use std::path::Path;
+
+use anyhow::bail;
+
+pub fn verify_checksum(path: &str, expected: &str) -> anyhow::Result<()> {
+  let file = Path::new(&path);
+  let checksum = sha256::try_digest(&file)?;
+
+  if checksum != expected {
+    bail!("Checksum mismatch, expected: {}, actual: {}", expected, checksum);
+  }
+
+  Ok(())
+}