wip(L26, side branch): every passage style walkable in both recipes (0/0/0); SW bridges look wrong

All 4 styles x both recipes pass capsule, open-air and naturalness audits, and full-view hashes are
deterministic. But the SW passage crosses 355 m of open SurfaceWorld sky as a ~2 km fragmented rock
ramp, which is not natural. L27 replaces long bridges with a shared ceiling-to-ground rock column.

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

Standalone/Source/OwnerWorldLoader.h

@@ -10,7 +10,11 @@
 #include "VoxelTerrainOpDefinition.h"
 
 #include <cmath>
+#include <array>
 #include <cstdint>
+#include <memory>
+#include <mutex>
+#include <unordered_map>
 
 struct FStandaloneParitySample
 {
@@ -20,6 +24,23 @@ struct FStandaloneParitySample
     int32 StrateIndex = INDEX_NONE;
 };
 
+struct FStandalonePassageBridgeRange
+{
+    std::size_t passageIndex=0;
+    std::size_t firstSegment=0;
+    std::size_t lastSegment=0;
+    std::uint64_t unsupportedSamples=0;
+    double unsupportedLengthMetres=0.0;
+    std::array<double,4> startPoint{};
+    std::array<double,4> endPoint{};
+};
+
+struct FStandalonePassageBridgeCache
+{
+    std::mutex mutex;
+    std::unordered_map<std::string,std::vector<FStandalonePassageBridgeRange>> byLayout;
+};
+
 struct FStandaloneOwnerWorld
 {
     std::unique_ptr<UVoxelSettings> Settings;
@@ -45,6 +66,8 @@ struct FStandaloneOwnerWorld
     std::uint32_t CoreVoxelSizeMicrons = 250000;
     std::uint32_t StrateLayoutChunkSizeMicrometres = 8000000;
     std::int64_t StrateLayoutChunkWidthSubvoxels = 8192;
+    std::shared_ptr<FStandalonePassageBridgeCache> PassageBridgeCache =
+        std::make_shared<FStandalonePassageBridgeCache>();
 };
 
 namespace StandaloneOwnerLoader