Modular architecture plan - split generator into focused modules
As the codebase grows toward 10k lines, the monolithic generator script should be split into focused modules: gaad_shapes.py (shape creation), gaad_genome.py (mutation and scaling), gaad_data.py (JSON read/write), gaad_generator.py (thin orchestrator/main loop). A shared geometry/diff module should also be created to resolve D052 (metrics duplication between tree and report). The addon-generator coupling via scene properties should be reviewed for robustness.