feat(graphics): improve rendering pipeline and docs

- Refactor D3D12 backend and RenderGraph module
- Update graphics RHI and core rendering components
- Add Random.hlsl shader include
- Regenerate API documentation and update user guides

doc/docs/getting-started.md

@@ -1 +1,88 @@
-# Getting Started
+# Getting Started with Ghost.Entities
+
+GhostEngine's Entity Component System (ECS) is a high-performance, Data-Oriented architecture designed for C# .NET 10. The ECS runtime is strictly AOT-compatible and focuses on unmanaged data structures to maximize cache locality and performance.
+
+## Initialization
+
+The core of the ECS is the `World`. A `World` contains an `EntityManager`, `ComponentManager`, and `SystemManager`. 
+
+To get started, you must create a `World`:
+
+```csharp
+using Ghost.Entities;
+
+// Create a new World with a default entity capacity of 16
+World world = World.Create();
+```
+
+## Creating Entities and Adding Components
+
+Entities are simply IDs that point to a combination of components. You use the `EntityManager` to create and modify them.
+
+First, define your unmanaged components:
+
+```csharp
+public struct Position : IComponent
+{
+    public float X, Y, Z;
+}
+
+public struct Velocity : IComponent
+{
+    public float X, Y, Z;
+}
+```
+
+Then, create entities and attach components:
+
+```csharp
+using Ghost.Core;
+using Misaki.HighPerformance.LowLevel.Buffer;
+
+// Creating a ComponentSet for fast archetype initialization
+using var scope = AllocationManager.CreateStackScope();
+var componentSet = new ComponentSet(
+    scope.AllocationHandle, 
+    ComponentTypeID<Position>.Value, 
+    ComponentTypeID<Velocity>.Value
+);
+
+// Create 1000 entities with both Position and Velocity
+world.EntityManager.CreateEntities(1000, componentSet);
+```
+
+## Adding Systems and Updating
+
+Systems contain the logic that operates on the component data. You add systems to the `SystemManager` and run them inside a loop.
+
+```csharp
+// Get the DefaultSystemGroup to attach systems
+var group = world.SystemManager.GetSystem<DefaultSystemGroup>();
+
+// Add custom systems
+group.AddSystem<MovementSystem>();
+
+// Sort systems based on their dependencies
+group.SortSystems();
+
+// Initialize all systems
+world.SystemManager.InitializeAll(new TimeData());
+
+// Update loop
+while (running)
+{
+    world.SystemManager.UpdateAll(timeData);
+    world.PlaybackEntityCommandBuffers();
+}
+
+// Cleanup at the end
+world.Dispose();
+```
+
+## Summary
+
+In GhostEngine ECS:
+1. **World** manages the lifecycle of your ECS data.
+2. **Components** (`IComponent`) are unmanaged data structures.
+3. **Entities** are logical containers combining those components into archetypes.
+4. **Systems** (`SystemBase`) execute logic over arrays of components using `EntityQuery`.