Add GameVersion domain and login validation

RecNet.Domain/GameVersions/GameVersion.cs

@@ -0,0 +1,31 @@
+using RecNet.Domain.Exceptions;
+
+namespace RecNet.Domain.GameVersions;
+
+public class GameVersion
+{
+    private GameVersion()
+    {
+    }
+
+    private GameVersion(string version, bool isValid)
+    {
+        Version = RequireValue(version, nameof(version));
+        IsValid = isValid;
+    }
+
+    public string Version { get; private set; } = string.Empty;
+    public bool IsValid { get; private set; }
+
+    public static GameVersion Create(string version, bool isValid)
+        => new(version, isValid);
+
+    public void MarkValid()
+        => IsValid = true;
+
+    public void MarkInvalid()
+        => IsValid = false;
+    
+    private static string RequireValue(string value, string parameterName)
+        => !string.IsNullOrWhiteSpace(value) ? value : throw new DomainException($"{parameterName} is required.");
+}

RecNet.Domain/GameVersions/IGameVersionRepository.cs

@@ -0,0 +1,12 @@
+namespace RecNet.Domain.GameVersions;
+
+public interface IGameVersionRepository
+{
+    Task<GameVersion?> GetAsync(string version, CancellationToken ct = default);
+
+    async Task<bool> IsValidAsync(string version, CancellationToken ct = default)
+    {
+        var gameVersion = await GetAsync(version, ct);
+        return gameVersion?.IsValid == true;
+    }
+}