Take the remaining I/O out of the domain and drop AppState.Instance

Scenery translations and load weights get repositories; AppState moves to the
application layer.

StarterNG.Tests/LoadWeightsTests.cs

@@ -0,0 +1,41 @@
+using StarterNG.Classes;
+using StarterNG.Domain.Vehicles;
+using StarterNG.Infrastructure.Vehicles;
+using StarterNG.Tests.Fakes;
+
+namespace StarterNG.Tests;
+
+public class LoadWeightsTests
+{
+    private static LoadWeightsRepository Repository(InMemoryFileSystem files)
+    {
+        var installation = new TestInstallation(files);
+        return new LoadWeightsRepository(files, installation.Paths, installation.Log);
+    }
+
+    [Fact]
+    public void Weights_are_read_from_the_pairs_in_the_file()
+    {
+        var files = new InMemoryFileSystem()
+            .WithFile(TestInstallation.At("data", "load_weights.txt"),
+                      "{\n  coal : 850 # węgiel\n  sand : 1600\n}");
+
+        var table = Repository(files).Table;
+
+        Assert.Equal(850, table.WeightOf("coal"));
+        Assert.Equal(1600, table.WeightOf("SAND"));
+    }
+
+    [Fact]
+    public void An_unknown_cargo_falls_back_to_the_default_weight()
+    {
+        Assert.Equal(LoadWeightsTable.DefaultWeight,
+                     Repository(new InMemoryFileSystem()).Table.WeightOf("nieznany"));
+    }
+
+    [Fact]
+    public void The_pantograph_pseudo_load_weighs_nothing()
+    {
+        Assert.Equal(0, new LoadWeightsTable().WeightOf(Dynamic.PantState));
+    }
+}