Fix cp1250 decoding, log unsupported loads

The repositories resolved GetEncoding(1250) in their constructors, before
anything registered CodePagesEncodingProvider - reads fell back to Latin-1 and
Polish characters came out as mojibake.

StarterNG.Tests/LegacyTextTests.cs

@@ -0,0 +1,38 @@
+using StarterNG.Infrastructure.Adapters;
+
+namespace StarterNG.Tests;
+
+public class LegacyTextTests
+{
+    [Fact]
+    public void The_game_code_page_resolves_without_anyone_registering_it_first()
+    {
+        // Regression guard: when this falls back, every Polish character in a
+        // scenery description comes out as Latin-1 mojibake ("Skład" as "Sk³ad").
+        Assert.False(LegacyText.IsFallback);
+        Assert.Equal(1250, LegacyText.CodePage1250.CodePage);
+    }
+
+    [Fact]
+    public void Polish_characters_survive_a_round_trip_through_it()
+    {
+        const string text = "Skład wygaszony pod wjazdowym. Strzebiń - Woźniki Śl.";
+
+        byte[] bytes = LegacyText.CodePage1250.GetBytes(text);
+
+        Assert.Equal(text, LegacyText.CodePage1250.GetString(bytes));
+    }
+
+    [Fact]
+    public void A_scenery_written_in_the_game_code_page_reads_back_intact()
+    {
+        var files = new StarterNG.Tests.Fakes.InMemoryFileSystem()
+            .WithLegacyFile(StarterNG.Tests.Fakes.TestInstallation.At("scenery", "td.scn"),
+                            "//$n Strzebiń - Woźniki Śl. '92\n//$d Skład wygaszony pod wjazdowym.");
+
+        var scenery = Assert.Single(new StarterNG.Tests.Fakes.TestInstallation(files).Sceneries.LoadAll());
+
+        Assert.Equal("Strzebiń - Woźniki Śl. '92", scenery.Name);
+        Assert.Equal("Skład wygaszony pod wjazdowym.", scenery.Description);
+    }
+}