test(save): 添加演出快照契约测试

校验 showcase/playTool/screen 的 SaveId 与还原顺序，
以及快照 section 的 JSON 序列化往返。

Assets/Editor/PresentationSnapshotContractTests.cs

@@ -0,0 +1,69 @@
+using AibisDream.SaveSystem;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using NUnit.Framework;
+
+namespace AibisDream.SystemEditor.Tests
+{
+    public sealed class PresentationSnapshotContractTests
+    {
+        [Test]
+        public void Providers_UseDistinctStableIdsAndRestoreBeforeScreen()
+        {
+            var showcase = new ShowcaseSnapshotProvider();
+            var playTool = new PlayToolSnapshotProvider();
+            var screen = new ScreenSnapshotProvider();
+
+            Assert.That(showcase.SaveId, Is.EqualTo("showcase"));
+            Assert.That(playTool.SaveId, Is.EqualTo("playTool"));
+            Assert.That(showcase.RestoreOrder, Is.LessThan(playTool.RestoreOrder));
+            Assert.That(playTool.RestoreOrder, Is.LessThan(screen.RestoreOrder));
+        }
+
+        [Test]
+        public void PresentationSections_RoundTripThroughSnapshotJson()
+        {
+            var source = new SaveSnapshot();
+            source.sections[SnapshotProviderIds.PlayTool] = new PlayToolSnapshotDto
+            {
+                isObjVisible = true,
+                objPicName = "证物",
+                isFullScreenVisible = true,
+                fullScreenPicName = "教室"
+            };
+            source.sections[SnapshotProviderIds.Showcase] = new ShowcaseSnapshotDto
+            {
+                displayMode = nameof(ShowcaseDisplayMode.Small),
+                picName = "D2S轱辘",
+                usesSplitLayers = true
+            };
+
+            var json = JsonConvert.SerializeObject(source);
+            var restored = JsonConvert.DeserializeObject<SaveSnapshot>(json);
+            var playTool = ((JObject)restored.sections[SnapshotProviderIds.PlayTool])
+                .ToObject<PlayToolSnapshotDto>();
+            var showcase = ((JObject)restored.sections[SnapshotProviderIds.Showcase])
+                .ToObject<ShowcaseSnapshotDto>();
+
+            Assert.That(playTool.isObjVisible, Is.True);
+            Assert.That(playTool.objPicName, Is.EqualTo("证物"));
+            Assert.That(playTool.isFullScreenVisible, Is.True);
+            Assert.That(playTool.fullScreenPicName, Is.EqualTo("教室"));
+            Assert.That(showcase.displayMode, Is.EqualTo(nameof(ShowcaseDisplayMode.Small)));
+            Assert.That(showcase.picName, Is.EqualTo("D2S轱辘"));
+            Assert.That(showcase.usesSplitLayers, Is.True);
+            Assert.That(restored.schemaVersion, Is.EqualTo(1));
+        }
+
+        [Test]
+        public void OldSnapshotWithoutPresentationSections_RemainsCompatible()
+        {
+            var restored = JsonConvert.DeserializeObject<SaveSnapshot>(
+                "{\"schemaVersion\":1,\"sections\":{}}");
+
+            Assert.That(restored.schemaVersion, Is.EqualTo(SaveSnapshotSchema.CurrentVersion));
+            Assert.That(restored.sections.ContainsKey(SnapshotProviderIds.PlayTool), Is.False);
+            Assert.That(restored.sections.ContainsKey(SnapshotProviderIds.Showcase), Is.False);
+        }
+    }
+}

Assets/Editor/PresentationSnapshotContractTests.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: aa21851c46624f77a67e29c86ec854c9