feat(model): build and read solids with the geometry kernel

Every 3-D solid OCS makes or opens now goes through cadkernel, which holds
analytic surfaces — a cylinder is a cylinder record, not a spline that looks
like one. That is what lets a solid built here be written back out as exact
ACIS instead of a triangulation, and a facetted export is a one-way door: the
next application to open the file would have no way back to the circle.

The Model tab's seven primitives, the Design-group booleans, 3DROTATE,
3DMIRROR, 3DALIGN, SLICE, SECTION, POLYSOLID and PYRAMID all come from the
kernel now, and `scene.solid_models` holds a `Body`. A mirrored solid needed
its own care before; the kernel reverses the loops on the way through, so it
comes back the right way out rather than lighting black.

EXTRUDE and REVOLVE sweep the profile `entities::curve` already defines, so a
circle, an arc-bulged polyline and a closed spline arrive as the same thing.
A circle extrudes into four cylinder patches rather than a run of chords, and
a profile turned about an axis becomes a cone, a sphere or a torus. A spline
profile has no analytic side wall and is refused rather than approximated.

ACIS goes both ways through the codec's own bridge: `lift` to read and
`append` to write. That drops the 679-line truck conversion and the planar-
only exporter, and the tessellator keeps its bespoke sampler as a fallback for
whatever the kernel cannot yet express — reported rather than passed off as
whole, since a mesh missing a wall looks finished.

truck-shapeops is no longer used and is gone from the manifest. truck-modeling
stays for now: fourteen files use it as a 3-D NURBS evaluator, which the
kernel has no answer for yet, and SWEEP and LOFT have no kernel operation
behind them either.

The two `automation` test failures are unchanged from before this and are not
caused by it.

Co-Authored-By: Claude Opus 5 <[email protected]>

src/command.rs

@@ -1158,7 +1158,7 @@ pub enum CmdResult {
     /// rendering). Ends the command.
     CommitSolid {
         entity: EntityType,
-        solid: Box<truck_modeling::Solid>,
+        solid: Box<acadrust::kernel::brep::Body>,
     },
     /// Commit an acadrust entity, end the command, and open the in-place text
     /// editor on it (used by MLEADER to type the annotation after placement).