Delete the dead material3 records, the empty placeholders and wrapper/ #31

What

Delete pythonx/compose/material3/icon.py, color_scheme.py, the 29 zero-byte material3/*.py placeholders, and pythonx/compose/wrapper/.

Why

icon.py and color_scheme.py are dead reflection code (mangled-name search, excluded by INTENT section 3) that nothing imports since #28; the placeholders have been empty since before the adaptation layer; wrapper/ is a retired 2024 shell. Every widget is served by the re-export rule. What icon.py recorded (Icon needs an ImageVector nothing bound produces; colour schemes need 36 Color parameters) stays in SPEC S5.3. Approved by the ecosystem lead. lite/ and test/ are the maintainer's decision (AGENTS.md section 16) and are not touched.

Done when

material3/ holds only init.py, wrapper/ is gone, a test pins both, and the wheel still builds.