Add OpenSCAD migration evaluation and flat-disk robot OpenSCAD prototype

[BenCaunt]

Motivation

• Evaluate OpenSCAD as an alternative to Build123D for the flat-disk-robot project, focusing on what is gained (interoperability, LLM friendliness) and what is lost (Python-first abstractions).
• Produce a near one-to-one reference port of the chassis/lid envelope to directly compare code, maintainability, and the process of migration.

Description

• Added an evaluation document at projects/flat-disk-robot/docs/openscad-migration-evaluation.md that summarizes tradeoffs, LLM usability, compatibility, a phased migration strategy, and acceptance criteria.
• Added a first-pass OpenSCAD prototype of the flat-disk robot at projects/flat-disk-robot/openscad/flat_disk_robot.scad that reproduces the chassis shell, perimeter wall, front/rear openings, wheel well cutouts, lid skirt/top, lid bosses, and M4 hole pattern.
• Updated projects/flat-disk-robot/README.md to link the OpenSCAD exploration artifacts for discoverability.
• The OpenSCAD port intentionally omits detailed STEP-based electronics/motor clearancing, press-fit details, decorative/logo features, and assembly metadata; it focuses on high-level geometric parity and mounting interfaces.

Testing

• Ran openscad --version to check for CLI availability, which failed because openscad is not installed in the environment.
• Ran pytest -q projects/flat-disk-robot/tests/test_geometry_invariants.py to exercise existing geometry invariants, which failed to collect due to a missing build123d dependency (ModuleNotFoundError: No module named 'build123d').
• No automated geometry tests succeeded in this environment; the artifacts are intended for local/CI validation where openscad and build123d toolchains are available.

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Codex Task

[github-actions]

SynthCAD CAD review

Compared 50cc8c6e6505 to ce9b67ac7651 for flat-disk-robot.

• Interactive diff viewer
• Workflow run and generated artifacts