1.3 Orientation value type

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/FrameProcessor/Domain/Orientation.cs

@@ -0,0 +1,34 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace FrameProcessor.Domain;
+
+[JsonConverter(typeof(OrientationJsonConverter))]
+public enum Orientation
+{
+    Landscape,
+    Portrait,
+}
+
+internal sealed class OrientationJsonConverter : JsonConverter<Orientation>
+{
+    public override Orientation Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        var s = reader.GetString();
+        return s switch
+        {
+            "landscape" => Orientation.Landscape,
+            "portrait" => Orientation.Portrait,
+            _ => throw new JsonException(
+                $"'{s}' is not a valid orientation. Expected 'landscape' or 'portrait'."),
+        };
+    }
+
+    public override void Write(Utf8JsonWriter writer, Orientation value, JsonSerializerOptions options)
+        => writer.WriteStringValue(value switch
+        {
+            Orientation.Landscape => "landscape",
+            Orientation.Portrait => "portrait",
+            _ => throw new JsonException($"Unknown orientation: {value}."),
+        });
+}