Fix ACF group mapping validation in push sync

[manuel-be-one]

Summary

This PR hardens the push sync when building ACF group mappings.

What changed

• Skip non-array group entries before mapping.
• Guard against key/value count mismatches before calling array_combine().
• Log mapping mismatches to simplify debugging malformed data.

Why

• array_combine() can generate invalid mappings or warnings when the ACF group shape is not what we expect.
• This fix prevents sync failures caused by malformed or inconsistent field data.

Testing

• Verified the push sync path with valid group data.
• Verified malformed group entries are skipped safely.
• Verified mismatched key/value counts no longer break the sync.