experiment: LivingPlane repeatable + standalone UE runtime module (L164)

Readback barrier fix (GL_TEXTURE_UPDATE_BARRIER_BIT before glGetTexImage); check_repeatability.py compares full-field
checksums across query/capture settings - Intel GPU PASS (3b9d45905c7aafff), llvmpipe PASS, mismatch control fails.
New runtime module VoxelForgeLivingPlane (separate from generation): RDG global shader (Shaders/LivingPlane.usf),
ping-pong RGBA32F render targets, actor with WPO plane and object inputs, no CPU readback. Compiles in Linux UE 5.7.
Windows build: Source/VoxelForgeLivingPlane/*, Shaders/LivingPlane.usf, VoxelForge.uplugin. Setup: UE-SETUP.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Experiments/LivingPlane/UNREAL-MAPPING.md

@@ -1,9 +1,9 @@
 # Unreal mapping note
 
-The prototype stores a two-channel height and vertical-velocity field in a pair of
-`RG32F` textures. A world-owned Unreal component could keep equivalent transient
-render graph textures and advance them with a compute pass. It should own simulation
-time and clear or restore its buffers when the world is recreated.
+The prototype stores height, vertical velocity, a recovering imprint, and a spare
+channel in a pair of `RGBA32F` textures. A world-owned Unreal component can keep
+equivalent transient render graph textures and advance them with a compute pass. It
+should own simulation time and clear or restore its buffers when the world is recreated.
 
 The sphere path becomes a world-space interaction event: position, contact radius,
 and impulse strength are supplied to the compute pass. For multiplayer or deterministic
@@ -21,3 +21,13 @@ default); do not mix metre distances and voxel counts in the wave solver.
 The current sample is an isolated visual field. Wiring this into `AVoxelWorld` would
 need an explicit owner for simulation lifetime, collision/update cadence, save/load,
 and the replication policy before it could affect shipped terrain.
+
+## L164 render-only Unreal implementation
+
+`Source/VoxelForgeLivingPlane/` now implements this render-only path as a separate
+runtime module. `AVoxelForgeLivingPlaneActor` owns two UAV-capable RGBA32F render
+targets, advances the wave, breathing, and imprint equations with an RDG global shader,
+and binds the current texture to its plane material. Blueprint/C++ supplies object
+position, radius, velocity, push, and active state. The actor does not call the
+generation modules and does not read the field back. Level setup and the material graph
+are in [UE-SETUP.md](UE-SETUP.md).