MeshTransform: Slice G — DetailGen3D detail-enhance backend (stretch)

[fernandotonon]

Part of #845 · Design: docs/MESH_TRANSFORM_DESIGN.md §4 · Stretch · Depends on Slice B (#847) plumbing.

DetailGen3D (VAST-AI, Apr 2025 — MIT code + weights, HF-verified): coarse mesh + conditioning image → detail-enhanced mesh via a data-dependent flow built ON TripoSG — architecturally a sibling of the variants pipeline (same vecset latent family; its own DiT weights + mesh conditioning à la Slice A/B).

Product shape: "Enhance (AI)" on a selected mesh — fix TripoSR blobbiness, add surface detail to photogrammetry / PS1-rip captures. Different seeds = detail variants.

• Export spike: DetailGen3D graphs → ONNX (expect the TripoSG recipe to apply; document deltas)
• Reuse Slice B sampling/encode/flow plumbing; conditioning image = source photo when the mesh came from generate3d, else an offscreen render
• CLI qtmesh enhance (or generate3d --enhance on an existing file), MCP tool, GUI button in the AI section
• License entry + hosting + docs per the epic's cross-cutting rules