Keep scenery files intact on save and follow them on disk

Saves keep comments and every byte they do not change. Faults in a scenery's
text are found and described. Files that change while the starter runs are
picked up without a manual reload.

StarterNG.Tests/Fakes/TestScenery.cs

@@ -0,0 +1,16 @@
+using StarterNG.Application.Abstractions;
+using StarterNG.Infrastructure.Adapters;
+using StarterNG.Infrastructure.Sceneries;
+
+namespace StarterNG.Tests.Fakes;
+
+/// <summary>The scenery reader over a fake clock and dice, for tests of what it makes of a text.</summary>
+public static class TestScenery
+{
+    /// <param name="now">The hour a scenery that names none starts at.</param>
+    public static SceneryParser Parser(DateTime? now = null) =>
+        new(new FixedClock(now ?? new DateTime(2026, 1, 1, 12, 0, 0)), new StubRandom());
+
+    public static SceneryRepository Repository(IFileSystem files) =>
+        new(files, new GamePaths("game"), TestLog.Over(files), Parser());
+}