chore: start transition layout — python into version-python/, scaffold version-rust/

- git mv of all existing files into version-python/ (history preserved)
- version-rust/: minimal cargo scaffold (edition 2024), no deps yet
- root AGENTS.md documents the transition rules and artifact/schema contract
- main is untouched; the python layout there stays as-is

version-rust/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("dlphelper {version} — Rust rewrite scaffold; modules are ported step by step, see version-rust/README.md", version = env!("CARGO_PKG_VERSION"));
+}