Pause the school on warning notices until the owner dismisses them.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/HSchool.Server.Tests/SchoolStoreTests.cs

@@ -44,6 +44,62 @@ public class SchoolStoreTests
         }
     }
 
+    [Fact]
+    public void Save_RoundTripsStickyNotices_AndOmitsThemWhenMissing()
+    {
+        var directory = Directory.CreateTempSubdirectory("h-school-store-");
+        try
+        {
+            var store = CreateStore(directory.FullName);
+            store.Save(new SchoolSave
+            {
+                Format = 3,
+                Id = 2,
+                Name = "Sticky",
+                GameTime = new DateTime(2012, 3, 31, 6, 0, 0, DateTimeKind.Utc),
+                Running = false,
+                SpeedIndex = 1,
+                Notices =
+                [
+                    new StickyNoticeSave
+                    {
+                        Id = 9,
+                        DefName = "GenerationFailed",
+                        Severity = 2,
+                        Pause = true,
+                        TtlMs = 0,
+                    },
+                ],
+            });
+
+            var withNotices = Assert.Single(store.LoadAll());
+            var sticky = Assert.Single(withNotices.Notices!);
+            Assert.Equal(9u, sticky.Id);
+            Assert.Equal("GenerationFailed", sticky.DefName);
+            Assert.True(sticky.Pause);
+
+            File.WriteAllText(
+                Path.Combine(directory.FullName, "3.json"),
+                """
+                {
+                  "format": 3,
+                  "id": 3,
+                  "name": "Plain",
+                  "gameTime": "2012-03-31T06:00:00Z",
+                  "running": false,
+                  "speedIndex": 0
+                }
+                """);
+
+            var plain = store.LoadAll().Single(save => save.Id == 3);
+            Assert.True(plain.Notices is null || plain.Notices.Count == 0);
+        }
+        finally
+        {
+            directory.Delete(recursive: true);
+        }
+    }
+
     private static SchoolStore CreateStore(string directory)
     {
         var options = Options.Create(new SimulationOptions { SavesDirectory = directory });