Run unchanged on the extended fork's GraalVM native-image and Kotlin/Native paths #110

What

pythonx-compose apps get two extra runtime choices from the extended fork, beside upstream Compose (default): a GraalVM native-image desktop executable and a Kotlin/Native desktop app. The host work is python-multiplatform #191; this issue is pythonx-compose's side.

Work

• Nothing in pythonx.* may rely on JVM-only behaviour (reflection, AWT); check the package against both paths.
• Guide: a page on choosing a path (upstream, extended GraalVM, extended K/N) with ppp/uv examples.
• The material3 mapping to the fork (Map pythonx.compose.material3 to the core-extended fork's material3, with a regression guard #54) and its regression guard apply to both paths.

When

pythonx-compose's turn, after python-multiplatform #191.

Done when

The notebook app runs unchanged on all three paths (CI through python-multiplatform's notebook E2E), and the guide documents the choice.