Allow skipping SimplifyResult in boolean operations

[PawelPisarek]

Fixes #272.

Booleans end with an unconditional newBody.SimplifyResult(true, true, 1e-3). On some shapes that step turns a valid solid into an invalid one, and the damage is silent — a later boolean on it returns an empty result while reporting HasErrors() === false and IsDone() === true. #272 has a self-contained reproduction.

This adds a simplify option to fuse, cut and intersect. It defaults to true, so nothing changes for existing callers; it only gives people hitting the problem a way out.

const blank = half.fuse(half.mirror("YZ", [382.2, 0, 0]), { simplify: false });

Measurements

Taken on the affected shapes (a lofted picture-frame moulding, 23 shape/size combinations):

	with simplification	without
solid valid	14 / 23	23 / 23
volume	—	unchanged (largest difference 0.00213 %, usually 0.00000 %)
face count	baseline	+4–5 % on curved shapes, +89 % on a straight one
time of the union	baseline	9–16 % faster

Why not verify and fall back instead

Checking the simplified result and reverting when it is invalid would fix everyone without an API change, so I measured it. BRepCheck_Analyzer costs 16–38 % of the boolean itself (29 ms against a 77 ms union; 269 ms against 1626 ms; 367 ms against 2341 ms), which makes the safe variant 7–22 % more expensive on every boolean for every user — to rescue a minority of shapes.

That trade-off felt like yours to make rather than mine, so this PR takes the cheap route. Happy to switch to the verify-and-fall-back version, or to make it a third mode (simplify: "safe"), if you prefer.

Checks

• tsc --noEmit clean
• vitest run in packages/replicad: 53 passed (49 existing + 4 new in __tests__/boolean-simplify.test.ts)