test: add asset path validity tests

tests/asset.rs

@@ -0,0 +1,14 @@
+use pacman::asset::Asset;
+use std::path::Path;
+use strum::IntoEnumIterator;
+
+#[test]
+fn test_asset_paths_valid() {
+    let base_path = Path::new("assets/game/");
+
+    for asset in Asset::iter() {
+        let path = base_path.join(asset.path());
+        assert!(path.exists(), "Asset path does not exist: {:?}", path);
+        assert!(path.is_file(), "Asset path is not a file: {:?}", path);
+    }
+}