Update CI to use macOS 15 and Xcode 16 for Swift 6.0

Required for Swift 6.0 toolchain compatibility.

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

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

Author: ldomaradzki

.github/workflows/release.yml

@@ -10,10 +10,13 @@ permissions:
 
 jobs:
   build:
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
       - uses: actions/checkout@v4
-      
+
+      - name: Select Xcode 16
+        run: sudo xcode-select -s /Applications/Xcode_16.1.app/Contents/Developer
+
       - name: Build for Apple Silicon
         run: |
           # Replace version in source code with git tag (strip v prefix)