Replace compile-time directives with target platform conditions (#143)

* Replace compile-time directives with target platform conditions

Use Package.swift target platform conditions instead of compile-time #if directives for EventSource dependency. This leverages Swift Package Manager's native dependency support for platform-specific targets at runtime rather than compile-time.

* Update reference for EventSource package

---------

Co-authored-by: Claude <[email protected]>
Co-authored-by: Mattt <[email protected]>

Author: 3 people

Package.swift

@@ -7,21 +7,16 @@ import PackageDescription
 var dependencies: [Package.Dependency] = [
     .package(url: "https://github.com/apple/swift-system.git", from: "1.0.0"),
     .package(url: "https://github.com/apple/swift-log.git", from: "1.5.0"),
+    .package(url: "https://github.com/mattt/eventsource.git", from: "1.1.0")
 ]
 
 // Target dependencies needed on all platforms
 var targetDependencies: [Target.Dependency] = [
     .product(name: "SystemPackage", package: "swift-system"),
     .product(name: "Logging", package: "swift-log"),
+    .product(name: "EventSource", package: "eventsource", condition: .when(platforms: [.macOS, .iOS, .tvOS, .visionOS, .watchOS]))
 ]
 
-// Add EventSource only on Apple platforms (non-Linux)
-#if !os(Linux)
-    dependencies.append(
-        .package(url: "https://github.com/loopwork-ai/eventsource.git", from: "1.1.0"))
-    targetDependencies.append(.product(name: "EventSource", package: "eventsource"))
-#endif
-
 let package = Package(
     name: "mcp-swift-sdk",
     platforms: [