Phase 5 of the decoupling refactor (behavior-preserving move):
- translator/ir.py: SolidWorks plugin JSON to backend-IR conversion (70 syms)
- translator/codegen.py: backend IR to build123d source generation (64 syms)
- translator/runtime_lib.py: frozen generated-script runtime library,
spliced into generate_build123d_code as *RUNTIME_LIB_LINES
- translator/common.py: helpers shared by both sides
- translator/__init__.py: full historical symbol surface re-exported
Generated-code equivalence verified byte-for-byte against the pre-split
output for a representative IR sample; py_compile clean.
