wip(L25, side branch): FI helix enclosed in a 13 m rock root; support never created in open air

Fixes the L24 ribbon (owner request). NOT merged: the open-air support gate leaves ~4,000 unsupported
samples on every SurfaceWorld-recipe passage style (TN -> SW), a walkability regression. L26 fixes that
on this branch. See Linux25/REPORT.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

Source/VoxelForge/Private/VoxelForgeCoreAdapter.cpp

@@ -485,7 +485,7 @@ bool BuildFloatingIslandStratumPlan(const UVoxelStrateManager* StrateManager,
     IslandPlan.topChunkZ = Slot.TopChunkZ;
     IslandPlan.bottomChunkZ = Slot.BottomChunkZ;
     auto& Recipe = IslandPlan.manifest.recipe;
-    Recipe.geometryVersion = 5;
+    Recipe.geometryVersion = 7;
     Recipe.layoutChunkWidthSubvoxels = LayoutChunkWidthSubvoxels;
     Recipe.seed = static_cast<std::uint32_t>(StrateManager->GetWorldSeed());
     Recipe.ownerVoxelSizeMicrons = static_cast<std::uint32_t>(std::llround(OwnerVoxelSizeCm * 10000.0));