Fix the startup crash on D3D12 with FXC: CPU fallback for the tessellation pipeline, FXC-friendly shader (#1098) (#1099)

* GPU tessellation: a pipeline the device cannot build falls back to CPU meshing instead of crashing (#1098)

Build the tessellation compute pipeline inside error scopes; TessGpu::new returns an error,
and the viewport logs it and meshes bodies on the CPU. A Windows CI job builds the pipeline
with D3D12's FXC on the WARP adapter.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* Tessellation shader: basis functions in one-dimensional local arrays, so D3D12's FXC compiles it (#1098)

FXC has to unroll loops that write an array inside a struct (Basis.n0/n1) or a 2-D array
(ndu) by a counter, and cannot with run-time trip counts (X3511). A2.2 basis functions in a
local 1-D array returned whole; derivatives from the degree p-1 functions; the pole step
offsets computed rather than indexed.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

---------

Co-authored-by: Claude Opus 5.5 <[email protected]>

Cargo.lock

@@ -3515,6 +3515,7 @@ name = "solidcraft-gpu"
 version = "0.10.0"
 dependencies = [
  "log",
+ "naga",
  "pollster 0.4.0",
  "solidcraft-geom",
  "solidcraft-kernel",