feat(linux): add graphical platform services

src/AcDream.App/Platform/GraphicalLegacyConfigurationMigrator.cs

@@ -0,0 +1,50 @@
+using AcDream.Runtime.Platform;
+
+namespace AcDream.App.Platform;
+
+internal static class GraphicalLegacyConfigurationMigrator
+{
+    private static readonly string[] FileNames =
+    [
+        "settings.json",
+        "keybinds.json",
+    ];
+
+    internal static IReadOnlyList<string> Migrate(
+        ApplicationPathSet paths)
+    {
+        ArgumentNullException.ThrowIfNull(paths);
+        if (paths.LegacyConfigDirectory is not { } legacyDirectory
+            || PathsEqual(legacyDirectory, paths.ConfigDirectory))
+        {
+            return [];
+        }
+
+        List<string>? migrated = null;
+        foreach (string fileName in FileNames)
+        {
+            string source = Path.Combine(legacyDirectory, fileName);
+            string destination = Path.Combine(
+                paths.ConfigDirectory,
+                fileName);
+            if (!File.Exists(source) || File.Exists(destination))
+                continue;
+
+            Directory.CreateDirectory(paths.ConfigDirectory);
+            File.Copy(source, destination, overwrite: false);
+            (migrated ??= []).Add(destination);
+        }
+
+        return migrated ?? [];
+    }
+
+    private static bool PathsEqual(string left, string right) =>
+        string.Equals(
+            Path.TrimEndingDirectorySeparator(
+                Path.GetFullPath(left)),
+            Path.TrimEndingDirectorySeparator(
+                Path.GetFullPath(right)),
+            OperatingSystem.IsWindows()
+                ? StringComparison.OrdinalIgnoreCase
+                : StringComparison.Ordinal);
+}