Restore the binder's Pythonic names (snake_case members and keywords) removed in 238119b7 #131

Maintainer: Pythonic argument/name conversion is a python-multiplatform feature. It existed since bd9bb9b (2026-08-14): on Kotlin-named modules the binding layer served members and keyword parameters in snake_case. 238119b (2026-10-02) removed it by over-reading AGENTS §12.1, which forbids renaming a namespace (androidx → pythonx), not converting member/parameter names.

Restore it: on Kotlin-named modules (androidx.* etc.) functions, members and keyword arguments are reachable by their snake_case (Pythonic) names; Kotlin names keep working too. Namespaces are not renamed; no pythonx synthesis; a real on-disk pythonx package still loads (§12.2). SPEC U-* and AGENTS §12.1 wording are corrected to say exactly this. Stubs carry the Pythonic names.

Completion: tests (restored from 238119b's reverted set where applicable) call androidx composables with snake_case names/keywords and pass; Kotlin names still pass; pythonx-compose's loading test still passes; all modules green.