Add DesignSystem test target

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: tdrhq

DesignSystem/Package.swift

@@ -13,5 +13,9 @@ let package = Package(
     ],
     targets: [
         .target(name: "DesignSystem"),
+        .testTarget(
+            name: "DesignSystemTests",
+            dependencies: ["DesignSystem"]
+        ),
     ]
 )

DesignSystem/Tests/DesignSystemTests/DesignSystemTests.swift

@@ -0,0 +1,5 @@
+import Testing
+@testable import DesignSystem
+
+@Test func example() {
+}