leo1200

Translate a native-JAX numerical kernel in this astronomix codebase into the matching Pallas backend kernel, following the conventions in `pallas_backend_implementation_guide.md`. Use when the user asks to "pallasify", "port to Pallas", "compile to Pallas", "regenerate the Pallas backend for X", or has just modified a `*_native` function and wants the `*_pallas` sibling refreshed. Pure code-translation: native JAX in, Pallas kernel out — the developer does NOT touch `_pallas` files by hand.