fix(unreal): U1 -- Unreal compiles again on L61; CoreGeometry asset section; versioned layout-unit upgrade

Windows MSVC catch-up after abyss L15-L61 (no Unreal there): 64-bit clipmap
shift (C4334), qualified VoxelForgeCore::WorldAssemblySubvoxelsPerVoxel, UHT
metadata and duplicate-signature fixes. Optional CoreGeometry section on
UVoxelStrateDefinition (native caves, lattice, profiled heightfields, named
stamps, rooms/tunnels; off/empty by default), resolved after passage planning.
VoxelForgeAssetVersion 2 converts strate height/transition/gap to metres on
load (exact, 0 m change on the owner's 5 assets; packages never saved).
Gates pass (SurfaceWorld, FloatingIslands, Core-off, M2, W1/W8/W16).
KNOWN REGRESSION vs L14 (2026-10-20, same command, same PC): full set 3.9 ->
5.37 s, worker-seconds 15.8 -> 30, LOD0 1.11 -> 1.69 s, ring 0.50 -> 0.80 s;
not yet attributed (Core L15-L61 vs Unreal side).
Report: Standalone/Research/WorldAssemblerM3/Unreal1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ARCHITECTURE.md

@@ -2292,6 +2292,30 @@ it also checks the orphan control, brute-force interval samples and the composed
 The Linux58 report contains the measured reachability, surface, peer-determinism, timing and capture
 results; the code path is not promoted to legacy Maze/VerticalShafts generation.
 
+### 8.55 Unreal CoreGeometry asset bridge and U1 asset version
+
+`UVoxelStrateDefinition::CoreGeometry` is optional and defaults to recipe `None` with no stamps,
+rooms, or tunnels. The Unreal adapter preserves the established passage planner, then resolves
+authored stamps and cavern graph records, then finalizes the layout. Stable names are required and
+are scoped by strate in Core; landmarks may target a stamp, room, or tunnel by that stable name.
+Core profile heightfields are restricted to SurfaceWorld. Native caves require the TunnelNetwork or
+Underwater archetype; native lattice requires Maze or VerticalShafts. Core recipe/version fields
+enter the resolved layout identity when selected. An imported manifest cannot be mixed with a
+per-strate profiled heightfield.
+
+The checked-out Core API contains stamp vocabularies V1, V2, and V3. Unreal uses V1 for the original
+stamp kinds and V3 for monolith/platform motifs, then combines and strictly validates the result.
+Research17 names V2, but the source API and motif vocabulary require V3; source was followed.
+Research27 water remains out of scope for U1.
+
+The shared VoxelForge custom asset version is 2: version 1 records the tunnel-floor slope migration;
+version 2 adds load-time conversion for inter-strate gap, strate height, and transition width. The
+saved strate-layout width is used, currently 8 m. Old packages are converted in memory and marked
+dirty, but U1 does not save them. This does not yet migrate the rest of Research8's reflected
+spatial-property inventory: legacy chunk distances, owner/Core voxel lengths and frequencies,
+placement vectors, and other centimetre fields remain in their prior units. The U1 report records
+the five BuildHost asset values, hashes, and remaining work.
+
 ## 9. Multiplayer model (listen-server first, dedicated-friendly)
 
 > **Status: transport is DESIGN ONLY — nothing is networked in-tree yet** (no `Replicated`/`HasAuthority`/RPCs; a