feat: module mangling & tree shaking

[AlphaKR93]

Summary

• Add project-wide module-level mangling (locals/nonlocals) and tree-shaking of unreachable/unused code.
• Resolve FFI library binaries so they're carried through project-wide processing correctly.

Test plan

• Run project-mode minify over a multi-module tree with FFI resources and confirm output is syntactically valid and importable.
• Verify mangled names don't collide across linked modules.