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.Core/Graphics/ShaderDescriptor.cs

@@ -52,6 +52,7 @@ public struct PassDescriptor
     public string[] includes;
     public KeywordsGroup[] keywords;
     public PipelineState localPipeline;
+    public string? hlsl;
 }
 
 public class ShaderDescriptor
@@ -61,6 +62,7 @@ public class ShaderDescriptor
     public PropertyDescriptor[] globalProperties = null!;
     public PropertyDescriptor[] properties = null!;
     public PassDescriptor[] passes = null!;
+    public string? hlsl;
 }
 
 public static class ShaderDescriptorExtensions