Fix cache directory creation in per_file_cache

Ensure parent directories exist before writing cache files. This fixes a test failure where cache writes would fail if the cache directory structure didn't already exist.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: technicalpickles

src/packs/caching/per_file_cache.rs

@@ -53,6 +53,17 @@ impl Cache for PerFileCache {
 
         let cache_data = serde_json::to_string(&cache_entry)
             .context("Failed to serialize references")?;
+
+        // Ensure parent directory exists
+        if let Some(parent) = empty_cache_entry.cache_file_path.parent() {
+            std::fs::create_dir_all(parent).map_err(|e| {
+                anyhow::Error::new(e).context(format!(
+                    "Failed to create cache directory {:?}",
+                    parent
+                ))
+            })?;
+        }
+
         let mut file = File::create(&empty_cache_entry.cache_file_path)
             .map_err(|e| {
                 anyhow::Error::new(e).context(format!(

tests/gitignore_test.rs

@@ -51,7 +51,8 @@ fn test_check_ignores_violations_in_gitignored_files(
 
 /// Test that list-included-files respects gitignore patterns.
 #[test]
-fn test_list_included_files_excludes_gitignored() -> Result<(), Box<dyn Error>> {
+fn test_list_included_files_excludes_gitignored() -> Result<(), Box<dyn Error>>
+{
     let output = Command::cargo_bin("pks")?
         .arg("--project-root")
         .arg("tests/fixtures/app_with_gitignore")