@W-24210682: Fix macOS native artifact deployment target

[mlischetti]

Summary

• Pin macOS release and main CI builds to macos-15 to prevent runner-version drift.
• Set the macOS deployment target to 11.0.
• Force GraalVM’s link step for both dw and dwlib to declare macOS 11.0 as the minimum supported OS.
• Make Python wheel tags deterministic and aligned with the native artifact contract:
  • macosx_11_0_arm64
  • macosx_11_0_x86_64
• Validate both native artifacts with otool in release and main CI.

Verification

• python3 -m pytest native-lib/python/tests/unit -q — 181 passed.
• Rebuilt dw and dwlib.dylib; both report minos 11.0.
• Built dataweave_native-100.100.100-py3-none-macosx_11_0_arm64.whl.
• Installed the rebuilt wheel on macOS 15 and ran DataWeave 2 + 2 successfully.
• Ran the rebuilt native CLI: dw run '2 + 2' → 4.

Context

macos-latest moved to macOS 26. The Python wheel tag was derived from the CI runner OS, and GraalVM’s native link step did not honor MACOSX_DEPLOYMENT_TARGET by itself. This caused v2.12.0 macOS artifacts to require macOS 26
despite the intended macOS 11 compatibility target.