nx_csg_scene.nx

nx_csg_scene.nx -- N-PRIMITIVE CSG. nx_csg_extract is hardwired to TWO primitives (a op b); real parts need many features folded into ONE watertight solid -- a toilet- cleaner head is plate MINUS pocket MINUS slots UNION neck UNION socket MINUS bore. This GROWS the capability by COMPOSING what already exists, adding no new geometry math: * the boolean algebra is the EXISTING nx_csg_combine_k (min/max + smooth-min fillet) * the surface mesher is the EXISTING marching-tetrahedra core (mt_tet, imported) * per-primitive ROTATION (about an arbitrary pivot) is the EXISTING nx_trig (cos/sin), applied by inverse-rotating the query point -- nx_sdf stays untouched * the only new thing is a LEFT-FOLD of the field over a list of (prim, op, fillet-k): field = combine_k(op[1], eval(p0), eval(p1), k[1]) ... combine_k(op[n-1], ., eval(p_{n-1}), k[n-1]) prim[0] is the seed (its op/k ignored). Robust by construction: SDF booleans can never fail/self-intersect the way B-rep does, and the marching grid is shared so the result is watertight by the same canonical-edge argument as nx_csg_extract. Output is a pipeline-native Q14-mm NxMesh -> nx_stl_write_mesh -> slicer -> G-code, exactly like every other sovereign solid. NOTE (tech-debt, logged not hidden): the grid+marching loop below is copied from nx_csg_extract with only the 2-prim field swapped for the scene field. The clean refactor is a field-eval callback in nx_csg_extract; deferred until NishiLang fn-ptr support is confirmed. license_tier: ORIGINAL