Make privacy manifest Apple-only via new resources target; add visionOS/macCatalyst

- Introduce CryptoSwiftResources target holding PrivacyInfo.xcprivacy.
- Conditionally depend on it for Apple platforms (iOS, macOS, tvOS, watchOS,
  macCatalyst, visionOS).
- Avoid SwiftPM resource bundle accessor and Foundation on non-Apple platforms.
- Add placeholder source to satisfy SwiftPM and move PrivacyInfo to new target.

Package.swift

@@ -2,6 +2,15 @@
 
 import PackageDescription
 
+let applePlatforms: [Platform] = [
+  .iOS,
+  .macOS,
+  .tvOS,
+  .watchOS,
+  .macCatalyst,
+  .custom("visionos")
+]
+
 let package = Package(
   name: "CryptoSwift",
   platforms: [
@@ -14,7 +23,15 @@ let package = Package(
     )
   ],
   targets: [
-    .target(name: "CryptoSwift", resources: [.copy("PrivacyInfo.xcprivacy")]),
+    // Keep the privacy manifest out of non-Apple builds so SwiftPM doesn't pull in
+    // Foundation just to synthesize a resource bundle accessor.
+    .target(name: "CryptoSwiftResources", resources: [.copy("PrivacyInfo.xcprivacy")]),
+    .target(
+      name: "CryptoSwift",
+      dependencies: [
+        .target(name: "CryptoSwiftResources", condition: .when(platforms: applePlatforms))
+      ]
+    ),
     .testTarget(name: "CryptoSwiftTests", dependencies: ["CryptoSwift"])
   ],
   swiftLanguageVersions: [.v5]

Sources/CryptoSwiftResources/Empty.swift

@@ -0,0 +1,16 @@
+//
+//  CryptoSwift
+//
+//  Copyright (C) 2014-2025 Marcin Krzyżanowski <marcin@krzyzanowskim.com>
+//  This software is provided 'as-is', without any express or implied warranty.
+//
+//  In no event will the authors be held liable for any damages arising from the use of this software.
+//
+//  Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
+//
+//  - The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation is required.
+//  - Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+//  - This notice may not be removed or altered from any source or binary distribution.
+//
+
+// Intentionally empty. SwiftPM requires at least one source file for a Swift target.