⚡ Bolt: Change scanner and cleaner actors to structs to fix parallel I/O bottleneck

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-28 - Avoid actor for parallel synchronous I/O
+**Learning:** Using an `actor` to manage a `withTaskGroup` where tasks invoke synchronous, blocking I/O (like `FileManager` operations) directly on the actor inadvertently serializes the tasks, preventing parallelism.
+**Action:** For stateless components interacting with thread-safe dependencies (like `FileManager`), use `struct`s or `nonisolated` methods to allow tasks to execute concurrently across threads.

Sources/Cacheout/Cleaner/CacheCleaner.swift

@@ -35,7 +35,7 @@
 import Foundation
 import AppKit
 
-actor CacheCleaner {
+struct CacheCleaner {
     private let fileManager = FileManager.default
 
     func clean(results: [ScanResult], nodeModules: [NodeModulesItem] = [], moveToTrash: Bool) async -> CleanupReport {

Sources/Cacheout/Scanner/CacheScanner.swift

@@ -26,7 +26,7 @@
 
 import Foundation
 
-actor CacheScanner {
+struct CacheScanner {
     private let fileManager = FileManager.default
 
     func scanAll(_ categories: [CacheCategory]) async -> [ScanResult] {

Sources/Cacheout/Scanner/NodeModulesScanner.swift

@@ -28,7 +28,7 @@
 
 import Foundation
 
-actor NodeModulesScanner {
+struct NodeModulesScanner {
     private let fileManager = FileManager.default
 
     /// Common directories where developers keep projects