Make Scenery a domain aggregate with no I/O

Parsing and loading move to Infrastructure/Sceneries. Weather becomes a value
object owning the "does this differ from the file" rule.

StarterNG.Tests/SceneryParserTests.cs

@@ -0,0 +1,154 @@
+using StarterNG.Infrastructure.Sceneries;
+using StarterNG.Tests.Fakes;
+
+namespace StarterNG.Tests;
+
+public class SceneryParserTests
+{
+    private static SceneryParser Parser(DateTime? now = null) =>
+        new(new FixedClock(now ?? new DateTime(2026, 5, 4, 9, 15, 0)), new StubRandom());
+
+    [Fact]
+    public void Directives_become_the_scenery_headline()
+    {
+        const string scn = """
+            //$l Śląsk
+            //$n Osobowy do Katowic
+            //$d Pierwszy opis
+            //$d drugi wiersz
+            //$i images/kato.jpg
+            """;
+
+        var scenery = Parser().Parse("scenery/kato.scn", scn);
+
+        Assert.Equal("Śląsk", scenery.Group);
+        Assert.Equal("Osobowy do Katowic", scenery.Name);
+        Assert.Equal("Pierwszy opis\ndrugi wiersz", scenery.Description);
+        Assert.Equal("images/kato.jpg", scenery.ImageName);
+        Assert.False(scenery.Archival);
+        Assert.Equal("kato", scenery.DisplayName);
+    }
+
+    [Fact]
+    public void The_a_directive_marks_a_scenery_archival()
+    {
+        var scenery = Parser().Parse("scenery/old.scn", "//$a\n//$n Stary\n");
+
+        Assert.True(scenery.Archival);
+    }
+
+    [Fact]
+    public void Attachments_take_a_label_from_the_rest_of_the_line()
+    {
+        const string scn = """
+            //$f 01 doc/rozklad.pdf Rozkład jazdy
+            //$f doc/mapa.png Mapa
+            //$f doc/notes.txt
+            """;
+
+        var scenery = Parser().Parse("scenery/x.scn", scn);
+
+        Assert.Collection(scenery.Attachments,
+            first =>
+            {
+                Assert.Equal("doc/rozklad.pdf", first.FilePath);
+                Assert.Equal("Rozkład jazdy", first.Label);
+            },
+            second =>
+            {
+                Assert.Equal("doc/mapa.png", second.FilePath);
+                Assert.Equal("Mapa", second.Label);
+            },
+            third =>
+            {
+                Assert.Equal("doc/notes.txt", third.FilePath);
+                Assert.Equal("notes.txt", third.Label);
+            });
+    }
+
+    [Fact]
+    public void Optional_includes_are_lifted_out_of_the_template()
+    {
+        const string scn = """
+            include zima.inc end //$optional 1, Sceneria zimowa
+            some content
+            endoptional
+            FirstInit
+            """;
+
+        var scenery = Parser().Parse("scenery/x.scn", scn);
+
+        var include = Assert.Single(scenery.Includes);
+        Assert.Equal("zima.inc", include.FilePath);
+        Assert.Equal("Sceneria zimowa", include.Desc);
+        Assert.Equal(1, include.Kind);
+        Assert.True(include.Selected);
+        Assert.DoesNotContain("zima.inc", scenery.Template);
+    }
+
+    [Fact]
+    public void Includes_of_kind_two_are_off_until_export_decides()
+    {
+        const string scn = """
+            include rozklad.inc end //$optional 2, Rozkład wbudowany
+            x
+            endoptional
+            """;
+
+        var include = Assert.Single(Parser().Parse("scenery/x.scn", scn).Includes);
+
+        Assert.Equal(2, include.Kind);
+        Assert.False(include.Selected);
+    }
+
+    [Fact]
+    public void Trainsets_are_parsed_and_replaced_by_placeholders()
+    {
+        const string scn = """
+            //$n Test
+            trainset pociag tor_1 10 0
+            node -1 -1 ep07-001 dynamic PKP/EP07 ep07 ep07.mmd 0 headdriver 0
+            endtrainset
+            FirstInit
+            """;
+
+        var scenery = Parser().Parse("scenery/x.scn", scn);
+
+        var trainset = Assert.Single(scenery.Trainsets);
+        Assert.True(trainset.Parsed);
+        Assert.Equal("pociag", trainset.Name);
+        Assert.Equal("tor_1", trainset.Track);
+        Assert.Contains("{{0}}", scenery.Template);
+        Assert.DoesNotContain("endtrainset", scenery.Template);
+    }
+
+    [Fact]
+    public void Vehicles_outside_a_trainset_are_collected_as_loose()
+    {
+        const string scn = """
+            node -1 -1 wagon_1 dynamic PKP/111A 111a 111a.mmd none 0 nobody 0 enddynamic
+            FirstInit
+            """;
+
+        var scenery = Parser().Parse("scenery/x.scn", scn);
+
+        var vehicle = Assert.Single(scenery.LooseVehicles);
+        Assert.Equal("wagon_1", vehicle.Name);
+        Assert.Equal("PKP/111A", vehicle.DataFolder);
+        Assert.Equal(new[] { "wagon_1" }, scenery.LooseVehicleNames);
+        Assert.DoesNotContain("enddynamic", scenery.Template);
+    }
+
+    [Fact]
+    public void A_malformed_loose_vehicle_is_reported_and_left_in_place()
+    {
+        const string scn = "node x -1 wagon_1 dynamic PKP/111A 111a 111a.mmd none 0 nobody 0 enddynamic\n";
+
+        var scenery = Parser().Parse("scenery/x.scn", scn);
+
+        Assert.Empty(scenery.LooseVehicles);
+        Assert.Equal(new[] { "wagon_1" }, scenery.LooseVehicleNames);
+        Assert.Contains(scenery.Faults, fault => fault.Contains("wagon_1"));
+        Assert.Contains("enddynamic", scenery.Template);
+    }
+}