Update README.md to include project description, developer documentation links, and license information.

tests/MrGameEng.Graphics.Tests/SpriteAnimationTests.cs

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+using Friflo.Engine.ECS;
+using Microsoft.Xna.Framework;
+using MrGameEng.Core;
+using MrGameEng.Graphics;
+using Xunit;
+
+namespace MrGameEng.Graphics.Tests;
+
+public class SpriteAnimationTests
+{
+    private static Texture2DRegion Region(int x) => new(null!, new Rectangle(x, 0, 16, 16));
+
+    private static SpriteAnimationClip Clip(bool loop, params int[] xs) =>
+        new(Array.ConvertAll(xs, Region), framesPerSecond: 10f, loop);
+
+    [Fact]
+    public void FrameAt_LoopingClip_WrapsAround()
+    {
+        var clip = Clip(loop: true, 0, 1, 2);
+
+        Assert.Equal(0, clip.FrameAt(0.00f).Bounds.X);
+        Assert.Equal(1, clip.FrameAt(0.10f).Bounds.X);
+        Assert.Equal(2, clip.FrameAt(0.25f).Bounds.X);
+        Assert.Equal(0, clip.FrameAt(0.30f).Bounds.X); // wrapped
+    }
+
+    [Fact]
+    public void FrameAt_NonLoopingClip_ClampsToLastFrame()
+    {
+        var clip = Clip(loop: false, 0, 1);
+
+        Assert.Equal(1, clip.FrameAt(10f).Bounds.X);
+    }
+
+    private sealed class AnimScene : Scene
+    {
+        public Entity Animated;
+        public SpriteAnimationClip Clip = SpriteAnimationTests.Clip(loop: false, 0, 1, 2);
+
+        protected override void OnLoad()
+        {
+            this.UseSpriteAnimation();
+            Animated = Store.CreateEntity(
+                new Sprite { Color = Color.White },
+                new SpriteAnimator(Clip));
+        }
+    }
+
+    [Fact]
+    public void AnimationSystem_AdvancesFrames_AndStopsAtEnd()
+    {
+        var context = new EngineContext();
+        var scene = new AnimScene();
+        context.Scenes.Switch(scene);
+
+        context.Clock.Advance(0.15f); // 10 fps → frame 1
+        context.Scenes.Update(context.Clock);
+        Assert.Equal(1, scene.Animated.GetComponent<Sprite>().Region!.Bounds.X);
+
+        context.Clock.Advance(1.0f); // far past the end of a non-looping clip
+        context.Scenes.Update(context.Clock);
+        Assert.Equal(2, scene.Animated.GetComponent<Sprite>().Region!.Bounds.X);
+        Assert.False(scene.Animated.GetComponent<SpriteAnimator>().Playing);
+    }
+}