refactor: rename aim to upm and extract appimage module

crates/upm-core/tests/install_payload.rs

@@ -0,0 +1,33 @@
+use std::fs;
+use std::os::unix::fs::PermissionsExt;
+use tempfile::tempdir;
+use upm_core::integration::install::stage_and_commit_payload;
+
+#[test]
+fn payload_commit_moves_staged_appimage_into_final_location() {
+    let root = tempdir().unwrap();
+    let staging_root = root.path().join("staging");
+    let payload_root = root.path().join("payloads");
+    fs::create_dir(&staging_root).unwrap();
+    fs::create_dir(&payload_root).unwrap();
+
+    let staged_path = staging_root.join("bat.download");
+    fs::write(&staged_path, b"\x7fELFAppImage").unwrap();
+    let final_payload_path = payload_root.join("bat.AppImage");
+    let outcome = stage_and_commit_payload(&staged_path, &final_payload_path).unwrap();
+
+    assert_eq!(
+        outcome
+            .final_payload_path
+            .extension()
+            .and_then(|ext| ext.to_str()),
+        Some("AppImage")
+    );
+    assert!(outcome.final_payload_path.exists());
+
+    let mode = fs::metadata(&outcome.final_payload_path)
+        .unwrap()
+        .permissions()
+        .mode();
+    assert_eq!(mode & 0o111, 0o111);
+}