fix(ci): use two-step yq approach for manifest merging (#1408)

The 'add' function doesn't exist in yq v4, causing parse errors.
Use a two-step approach that was tested locally:
1. Collect all files with '[.files] | flatten'
2. Load merged files into first manifest with 'load()'

Tested locally with yq v4.50.1

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: AndyMik90

.github/actions/merge-macos-manifests/action.yml

@@ -80,9 +80,12 @@ runs:
           echo "Installed yq version:"
           yq --version
 
-          # Merge the files arrays from both manifests using eval-all
-          # Use single line to avoid shell/YAML parsing issues
-          yq eval-all 'select(fileIndex == 0) * {"files": ([.[].files] | add)}' "$intel_manifest" "$arm64_manifest" > "${{ inputs.output-path }}/latest-mac.yml"
+          # Merge the files arrays from both manifests using two-step approach
+          # Step 1: Collect all files from both manifests into a temp file
+          yq eval-all '[.files] | flatten' "$intel_manifest" "$arm64_manifest" > /tmp/merged-files.yml
+
+          # Step 2: Replace files array in first manifest with merged files
+          yq eval '.files = load("/tmp/merged-files.yml")' "$intel_manifest" > "${{ inputs.output-path }}/latest-mac.yml"
 
           echo "Merged manifest contents:"
           cat "${{ inputs.output-path }}/latest-mac.yml"