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.Entities.Test/EntityQueryTest.cs

@@ -48,7 +48,7 @@ public partial class EntityQueryTest : ITest
         _world.EntityManager.CreateEntities(entities, set);
 
         var queryID = new QueryBuilder().WithAllRW<Transform>().Build(_world);
-        ref var query = ref _world.GetEntityQueryReference(queryID);
+        ref var query = ref _world.ComponentManager.GetEntityQueryReference(queryID);
 
         _world.AdvanceVersion();