Add support for tvOS (#254)

* Add support for tvOS in Package.swift and GPU.swift

* Fix tvOS availability check in GPU.swift

Replace conditional compilation with proper availability check for tvOS 17.0
as suggested in PR review. The architecture property is available on tvOS 17.0
and later according to Apple documentation.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: guitaripod

Package.swift

@@ -10,6 +10,7 @@ let package = Package(
     platforms: [
         .macOS("13.3"),
         .iOS(.v16),
+        .tvOS(.v16),
         .visionOS(.v1),
     ],
 

Source/MLX/GPU.swift

@@ -340,7 +340,7 @@ public enum GPU {
 
         if let device = MTLCreateSystemDefaultDevice() {
             let architecture: String
-            if #available(macOS 14.0, iOS 17.0, *) {
+            if #available(macOS 14.0, iOS 17.0, tvOS 17.0, *) {
                 architecture = device.architecture.name
             } else {
                 architecture = device.name