fix(hatch): render fills via the per-fragment in_polygon test again

The batched hatch path pre-triangulated every boundary on the CPU
(PR#300) with no cap on the resulting vertex buffer. A hatch-dense
drawing (13k solid-filled hatches) built a ~6.75 GB `hatch_batched.vertex`
buffer and panicked in `Device::create_buffer` (device max 256 MB), after
a long stall spent triangulating on load.

Drop the CPU triangulation and always draw each hatch as its AABB quad
(6 verts) with `poly_test = 1`, letting the shader resolve inside/outside
per fragment against the uploaded boundary — the path the shader always
kept as a fallback. The vertex buffer is now 6 verts/hatch regardless of
boundary complexity, so no drawing can overflow it. The interaction-LOD
flicker PR#300 addressed no longer occurs (OCS_HATCH_LOD defaults off).
Removes the now-unused hatch_tess triangulation module.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/scene/pipeline/mod.rs

@@ -1,6 +1,5 @@
 pub mod face3d_gpu;
 pub mod hatch_batched_gpu;
-pub mod hatch_tess;
 pub mod hatch_gpu;
 pub mod image_gpu;
 pub mod mesh_gpu;