Phase G: scaffold .NET 10 + SignalR backend (engine port + hub + auth)

- server/ monorepo: Hokm.Engine (C# port of TS engine+AI, validated by sim),
  Hokm.Server (SignalR GameHub, in-memory matchmaking/rooms, server-side turn
  timers + bot fill + disconnect handling, per-seat state broadcast), Hokm.Sim
- JWT dev auth (OTP 1234 + email); CORS for the Next client; /hub/game
- NuGet restored from mirrors (Soroush Nexus + Liara); NuGetAudit off
- README + .NET .gitignore; static class Engine renamed Rules (namespace clash)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/tools/Hokm.Sim/Hokm.Sim.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\Hokm.Engine\Hokm.Engine.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>