Fix macOS archive structure to place libskia.a at top level

Use zip -j flag to store libskia.a without directory paths, ensuring
all three macOS archives (x64, arm64, universal2) have libskia.a at
the root when unpacked, as expected by skia-pathops download script.

Author: anthrotype

.github/workflows/ci.yml

@@ -26,14 +26,10 @@ jobs:
         # Build universal2 (creates x64, arm64, and universal2 binaries)
         ./build.sh
 
-        # Create separate archives for each architecture with proper directory structure
-        mkdir -p dist/libskia-mac-x64 dist/libskia-mac-arm64 dist/libskia-mac-universal2
-        cp build/x64/libskia.a dist/libskia-mac-x64/
-        cp build/arm64/libskia.a dist/libskia-mac-arm64/
-        cp build/libskia.a dist/libskia-mac-universal2/
-        (cd dist && zip -r libskia-mac-x64.zip libskia-mac-x64)
-        (cd dist && zip -r libskia-mac-arm64.zip libskia-mac-arm64)
-        (cd dist && zip -r libskia-mac-universal2.zip libskia-mac-universal2)
+        # Create separate archives for each architecture
+        zip -j dist/libskia-mac-x64.zip build/x64/libskia.a
+        zip -j dist/libskia-mac-arm64.zip build/arm64/libskia.a
+        zip -j dist/libskia-mac-universal2.zip build/libskia.a
     - uses: actions/upload-artifact@v4
       with:
         name: libskia-mac-x64