wip(L27, side branch): passages cross open voids inside shared natural rock columns

Unsupported passage runs > 12.5 m become a solid relief-bearing column (ceiling/island to
ground, flared base) with the helix inside, for every recipe; FI anchor uses the same path.
All 4 styles x both recipes: 0/0/0, 0 open-air, naturalness pass; no-long-bridge audit (L26
fails it). Deterministic, Clang = GCC. Look approved; cost +35% SW / +19% FI blocks merge (L28).

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 = 7;
+    Recipe.geometryVersion = 8;
     Recipe.layoutChunkWidthSubvoxels = LayoutChunkWidthSubvoxels;
     Recipe.seed = static_cast<std::uint32_t>(StrateManager->GetWorldSeed());
     Recipe.ownerVoxelSizeMicrons = static_cast<std::uint32_t>(std::llround(OwnerVoxelSizeCm * 10000.0));