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

VoxelForge.uplugin

@@ -31,6 +31,11 @@
 			"Type": "Runtime",
 			"LoadingPhase": "Default"
 		},
+		{
+			"Name": "VoxelForgeLivingPlane",
+			"Type": "Runtime",
+			"LoadingPhase": "Default"
+		},
 		{
 			"Name": "VoxelForgeEditor",
 			"Type": "Editor",