Add NEMA34 motor support

[seveibar]

Adds nema34 strings and nemaSize: 34 to the shared NEMA contract. The representative 86 × 80 mm envelope, 69.6 mm mounting pitch, 6.5 mm through-flange holes, 73 mm pilot, and 14 × 32 mm round shaft follow the STEPPERONLINE dimension drawing; the keyway is omitted.

NEMA34 defaults now follow the supplied STEPPERONLINE product photo: a rounded stepped body/rear profile, plain rear casting, and 2 mm wires with a 25 mm visible length exiting at 90 degrees beside the rear of the body. cornerProfile / stepped / chamfered and rearCornerChamfer / rearchamfer configure the profiles. Shoulder depth is the chamfer value divided by sqrt(2), with fillets up to 4 mm; default body/rear values are 24 mm. Optional rear bores/screws use an illustrative 40 mm pitch. These photo-based details are not manufacturing dimensions or frame guarantees.

Wire references follow the stepped outline, including diagonal exits and hidden wires. Validation checks through-hole clearance, optional rear screw clearance, and wire/connector fit. Existing NEMA8/17/23 default definitions remain covered.

Validation: all 236 tests pass (4951 assertions), plus typecheck, format check, and build. Geometry and visual preview: tscircuit/jscad-electronics#500.

[tscircuitbot]

---

Thank you for your contribution! 🎉

PR Rating: ⭐⭐⭐
Impact: Major

Track your contributions and see the leaderboard at: tscircuit Contribution Tracker

---