TASK 3 milestone 1: webcam capture (MediaCapture CPU-first, CameraManager refcount, picker, clip/mirror, schema v2, tests)

Services/MediaCaptureCameraEnumerator.cs

@@ -0,0 +1,15 @@
+using Windows.Devices.Enumeration;
+
+namespace ytLive.Services;
+
+public sealed class MediaCaptureCameraEnumerator : ICameraEnumerator
+{
+    public async Task<IReadOnlyList<CameraDeviceInfo>> GetCamerasAsync()
+    {
+        var devices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);
+        var result = new List<CameraDeviceInfo>(devices.Count);
+        foreach (var device in devices)
+            result.Add(new CameraDeviceInfo(device.Id, device.Name));
+        return result;
+    }
+}