Add HSchool.Content project for JSONC definitions, catalog, and map validation. Update solution structure to include new content and tests projects. Enhance school management to support mod packs and map instances, ensuring proper loading and validation. Revise documentation to reflect these changes and update tests for new functionality.

tests/HSchool.Content.Tests/VanillaCoreTests.cs

@@ -0,0 +1,25 @@
+namespace HSchool.Content.Tests;
+
+public class VanillaCoreTests
+{
+    [Fact]
+    public void CoreDefaultMap_PassesValidation()
+    {
+        var root = Path.Combine(AppContext.BaseDirectory, "vanilla");
+        Assert.True(Directory.Exists(root), $"Vanilla core pack was not copied to {root}.");
+
+        var documents = PackDocuments.FromDirectory(CatalogLoader.CorePackId, root);
+        var catalog = new CatalogLoader().Load([CatalogLoader.CorePackId], documents);
+        var map = CatalogLoader.LastDefaultMap([CatalogLoader.CorePackId], documents);
+
+        Assert.NotNull(map);
+        MapValidator.Validate(map, catalog);
+
+        Assert.Equal("SchoolYard", catalog.Territories["SchoolYard"].DefName);
+        Assert.True(catalog.Rooms["Corridor"].Slots.Count == 0);
+        Assert.Equal(["Principal"], catalog.PositionsFor(DefKind.Room, "PrincipalsOffice"));
+        Assert.Equal("Кабинет директора", catalog.Label("ru", catalog.Rooms["PrincipalsOffice"]));
+        Assert.Equal("Principal's office", catalog.Label("en", catalog.Rooms["PrincipalsOffice"]));
+        Assert.Equal(["Sit"], catalog.Things["DirectorsChair"].Actions);
+    }
+}