Add high-performance material/shader system (Ghost.Shader.Concept)

Introduces a new Ghost.Shader.Concept project implementing a modern, data-oriented material and shader system with:
- Global/local keyword bitsets (fast O(1) ops, 64 bytes)
- Multi-pass shader program and per-pass render state overrides
- Thread-safe, 16-byte aligned material property blocks
- Material pooling to reduce GC pressure
- Batch renderer for efficient PSO grouping and async variant warmup
- Full demo (Program.cs) and extensive documentation (ARCHITECTURE.md, README.md, PROJECT_SUMMARY.md)
- Minor integration: new enums, doc updates, and keyword handling in existing code

No breaking changes to the existing engine; all new code is isolated. This serves as a reference implementation for high-performance, extensible material/shader architectures.

Ghost.Shader/Compiler/Parser/KeywordsBlock.cs

@@ -54,11 +54,11 @@ internal class KeywordsBlock : IBlockParser<List<FunctionCallDeclaration>, List<
             var group = new KeywordsGroup();
             switch (keyword.name.lexeme)
             {
-                case TokenLexicon.KnownFunctions.DYNAMIC:
-                    group.type = KeywordType.Dynamic;
+                case TokenLexicon.KnownFunctions.LOCAL:
+                    group.space = KeywordSpace.Local;
                     break;
-                case TokenLexicon.KnownFunctions.STATIC:
-                    group.type = KeywordType.Static;
+                case TokenLexicon.KnownFunctions.GLOBAL:
+                    group.space = KeywordSpace.Global;
                     break;
                 default:
                     errors.Add(new SDLError

Ghost.Shader/Compiler/Token.cs

@@ -141,8 +141,8 @@ internal static class TokenLexicon
         public const string MESH_SHADER = "ms";
         public const string PIXEL_SHADER = "ps";
         public const string COMPUTE_SHADER = "cs";
-        public const string DYNAMIC = "dynamic";
-        public const string STATIC = "static";
+        public const string LOCAL = "local";
+        public const string GLOBAL = "global";
         public const string FALLBACK = "fallback";
     }
 
@@ -208,8 +208,8 @@ internal static class TokenLexicon
         KnownFunctions.PIXEL_SHADER,
         KnownFunctions.MESH_SHADER,
         KnownFunctions.COMPUTE_SHADER,
-        KnownFunctions.DYNAMIC,
-        KnownFunctions.STATIC,
+        KnownFunctions.LOCAL,
+        KnownFunctions.GLOBAL,
     };
 
     private static readonly HashSet<string> s_types = new()