standalone: the owner's world outside Unreal -- bit-identical density, D3D11 fly-through viewer

Standalone/ (C++20, MSVC /O2 /arch:AVX2 /fp:precise, Build.ps1): copied density pipeline, op stack,
cave morphology, passages, strate manager/composer, noise, DetSinCos, mesher, clipmap selection,
with a UE compatibility layer (Compat/). Owner data exported once to Standalone/data/owner_world.json
by a default-off explore-commandlet exporter (the only plugin-source change). 25 cm voxels.
Parity: seed 0, 3,436 samples (strate edges, negative/far coords, rooms, tunnels, passages,
landings): bit-identical. Viewer: full 7-level clipmap, per-level toggles 1-7, T = round winding
tunnels (standalone option), N/P seed, F wireframe.
Timing NOT yet a baseline: 515 s for 12,054 tiles (L0 70 s, L6 296 s); the compat TMap/TSet are
vector-backed with linear lookup, which the plugin's caches do not expect.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

.gitignore

@@ -9,6 +9,12 @@
 !/Source/
 !/Source/**
 
+# Portable CPU generator and D3D11 viewer.
+!/Standalone/
+!/Standalone/**
+/Standalone/Build/
+/Standalone/bin/
+
 # The guarded single-entry test harness is source, not generated output.
 !/Tools/
 !/Tools/**