Initial: ComfyUI + Trellis2 on Rocky 9.x / RTX 4090

Documents all pitfalls encountered during setup:
- CUDA arch mismatch (sm_120 vs sm_89) — source rebuild needed
- utils3d empty pip package → GitHub fork required
- transformers v5 DINOv3 API change → sed patch
- xformers version pinning (0.0.33.post2 for torch 2.9.1)
- Missing Eigen headers for cumesh build
- visualbruno forks needed for o_voxel and cumesh (newer functions)
- /tmp disk space issues during pip builds

Includes:
- SETUP.md: Full step-by-step guide
- requirements.txt: Pinned dependency versions
- fix_transformers_v5.sh: Apply DINOv3 layer patch
- build_cuda_extensions.sh: One-shot source build of all CUDA extensions

requirements.txt

@@ -0,0 +1,29 @@
+# ComfyUI base (from ComfyUI/requirements.txt)
+# Install with: pip install -r requirements_comfyui.txt
+-r https://raw.githubusercontent.com/comfyanonymous/ComfyUI/master/requirements.txt
+
+# Trellis2 Python dependencies
+meshlib
+requests
+pymeshlab
+opencv-python
+scipy
+open3d
+plotly
+rembg
+
+# Core
+torch==2.9.1
+torchvision==0.24.1
+torchaudio==2.9.1
+
+# Attention backends
+xformers==0.0.33.post2
+natten==0.21.5+torch290cu128
+
+# Source-built CUDA extensions (use pip install from GitHub, see SETUP.md)
+# flex_gemm @ git+https://github.com/JeffreyXiang/FlexGEMM.git
+# o_voxel @ git+https://github.com/visualbruno/TRELLIS.2.git#subdirectory=o-voxel
+# cumesh @ git+https://github.com/visualbruno/CuMesh.git
+# nvdiffrast @ git+https://github.com/NVlabs/nvdiffrast.git
+# utils3d @ git+https://github.com/EasternJournalist/utils3d.git@3fab839