Cleaning the generated hearth

Owner authorized Blender cleanup and Unity integration. The raw 15 October TripoSR GLB remains unchanged, SHA256 ca9d8b30db2f203738e61987f7d9902d57993ad2b2d777ff6635bfab4f094cfb. Measured in Blender 5.2.2 LTS on 16 October: raw 2,591 vertices / 5,140 triangles / 84 boundary edges; cleaned v2 2,568 vertices / 5,136 triangles / zero nonmanifold edges. Grounded footprint at most 1.6 m and solid height 0.4 m. Original vertex colors are baked into one packed 512×512 albedo. Seven saved-source export checks passed. A first bake selected an imported empty and failed before rendering; a completed v1 then exposed wrong-axis flattening and is retained. Captures 20261016T000443377095-1ffe11280855 and 20261016T000447499670-4fa59e856f94 preserve that iteration. v2 front and underside were inspected with their exact staged metadata and individually approved. Final source hash 770420f022260b2d91959e2e2cbc575953f010186281bc3e584f99bd7b4790a0. A separate visible Bonfire Review app preserves the tree/other Blender windows. Reconstruction remains softened; hole caps may be dark and inferred surfaces are not ground truth. No opaque flame geometry was added. See docs/bonfire-asset.md. Next: verify the imported solid structure with existing campfire effects and behavior in Unity; this Blender evidence does not prove game integration.