Refactor: variant-aware shader/material pipeline overhaul

Major architectural update to graphics/material/shader system:
- Introduced strongly-typed key structs (Key64/Key128) for passes, variants, and pipelines; removed legacy key types.
- Implemented robust hashing and key generation utilities for efficient variant and pipeline lookup/caching.
- Shader compiler now compiles/caches all keyword variants using new key system; includes handled as lists.
- Switched to push constant root signature for per-draw data; updated HLSL and C# codegen accordingly.
- Refactored Material, Shader, and Pass data structures for cache efficiency and variant support.
- Pipeline library and PSO management now use 128-bit keys and variant-specific caching.
- Replaced WorldNode with SceneNode in editor/scene graph; introduced ComponentManager for archetype/query management.
- Migrated math utilities to Misaki.HighPerformance.Mathematics; updated editor controls.
- Updated all HLSL and codegen for new buffer/push constant layouts and macros.
- Misc: project reference cleanup, D3D12 Work Graph support, doc updates, and code modernization.

Ghost.Editor.Core/SceneGraph/EditorSceneManager.cs

@@ -0,0 +1,53 @@
+using Ghost.Editor.Core.Progress;
+using Ghost.Editor.Core.Resources;
+using Ghost.Editor.Core.Utilities;
+using System.Text.Json;
+
+namespace Ghost.Editor.Core.SceneGraph;
+
+public enum OpenWorldMode
+{
+    Single,
+    Additive,
+    AdditiveWithoutLoading
+}
+
+public static class EditorSceneManager
+{
+    // TODO: Use guid keys instead of string paths for better performance and uniqueness
+    private static readonly Dictionary<string, SceneNode> s_loadedWorlds = new();
+    public static IEnumerable<SceneNode> LoadedWorlds => s_loadedWorlds.Values;
+
+    public static event Action<SceneNode>? OnWorldLoaded;
+    public static event Action<SceneNode>? OnWorldUnloaded;
+
+    public static async Task LoadSceneAsync(string worldPath)
+    {
+        if (s_loadedWorlds.ContainsKey(worldPath)
+            || !File.Exists(worldPath)
+            || Path.GetExtension(worldPath) != FileExtensions.SCENE_FILE_EXTENSION)
+        {
+            return;
+        }
+
+        var progressService = EditorApplication.GetService<IProgressService>();
+        progressService.ShowIndeterminateProgress("Loading world...");
+
+        foreach (var world in s_loadedWorlds)
+        {
+            world.Value.Unload();
+            OnWorldUnloaded?.Invoke(world.Value);
+        }
+
+        await using var readStream = new FileStream(worldPath, FileMode.Open, FileAccess.Read, FileShare.Read);
+        var deserializedScene = await JsonSerializer.DeserializeAsync<SceneNode>(readStream, Engine.Resources.EngineResource.defaultSerializerOptions) ?? throw new Exception("Deserialization failed.");
+
+        s_loadedWorlds.Clear();
+
+        s_loadedWorlds[worldPath] = deserializedScene;
+        await deserializedScene.LoadAsync();
+
+        progressService.HideProgress();
+        OnWorldLoaded?.Invoke(deserializedScene);
+    }
+}