Refactor render graph & DSL; remove material system

- Major optimization of Ghost.RenderGraph.Concept: pooled resources, zero-allocation hot paths, explicit queue types, and batch barrier APIs.
- Migrated Ghost.DSL shader compiler to ANTLR4-based parser; removed hand-written parser, added grammar files and semantic model conversion.
- Added CollectionPool/ListPool for pooled list management.
- Updated documentation for new architecture and performance.
- Removed Ghost.Shader.Concept (material/material system) from repo and solution.
- README.md replaced with a brief project statement.

Ghost.RenderGraph.Concept/Ghost.RenderGraph.Concept.csproj

@@ -7,4 +7,12 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\Ghost.Core\Ghost.Core.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Folder Include="New\" />
+  </ItemGroup>
+
 </Project>