Initial LittleSim scaffold on the mrgameeng engine submodule

God-game: minimal graphics, deep simulation. The engine lives in the
engine/ git submodule and its sources plus test suites are part of
LittleSim.sln, so engine and game are developed in one editor window.

Playable skeleton: seed-deterministic terrain (smoothed height field ->
water/sand/grass/forest/mountain tinted cells), 80 wandering villagers
on a Y-sorted layer, god camera (WASD pan, wheel zoom, world-bounds
clamp), HUD and the dev console with a 'regen [seed]' command.

CLAUDE.md sets the game rules: simulation-first, one-seed determinism,
simulation/presentation split, a console command for every mechanic.
Design docs in Russian under docs/.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Directory.Build.props

@@ -0,0 +1,12 @@
+<Project>
+
+  <PropertyGroup>
+    <LangVersion>latest</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <InvariantGlobalization>true</InvariantGlobalization>
+    <RootNamespace>$(MSBuildProjectName)</RootNamespace>
+  </PropertyGroup>
+
+</Project>