Fix Swift 6 strict concurrency errors

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ivanvorobei

Sources/SwiftBoost/Foundation/Delay.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-public func delay(_ delay: TimeInterval, closure: @escaping ClosureVoid) {
+public func delay(_ delay: TimeInterval, closure: @escaping @Sendable () -> Void) {
     let when = DispatchTime.now() + delay
     DispatchQueue.main.asyncAfter(deadline: when) {
         closure()

Sources/SwiftBoost/Foundation/Extensions/URLSessionExtension.swift

@@ -57,7 +57,7 @@ public extension URLSession {
         method: HTTPMethod,
         body: [String: Any?]? = nil,
         contentTypeHeader: ContentType? = nil,
-        completion: @escaping (AppError?, Data?, HTTPURLResponse?) -> Void
+        completion: @escaping @Sendable (AppError?, Data?, HTTPURLResponse?) -> Void
     ) {
         guard let url = URL(string: url) else {
             completion(AppError.invalidURL(url), nil, nil)

Sources/SwiftBoost/Foundation/Logger.swift

@@ -78,7 +78,7 @@ public enum Logger {
         var levels: [Level] = []
         var fileNameMode: FileNameMode = .show
 
-        static var shared = Configurator()
+        nonisolated(unsafe) static var shared = Configurator()
         private init() {}
     }
 }