fix: resolve build errors with missing using directive and variable name conflict

Co-authored-by: aider (openrouter/anthropic/claude-sonnet-4) <aider@aider.chat>

Services/Compositor/SceneCompositor.cs

@@ -1,3 +1,4 @@
+using ytLive.Helpers;
 using ytLive.Models;
 
 namespace ytLive.Services.Compositor;

Services/MediaCaptureFrameSource.cs

@@ -317,16 +317,16 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
                 }
 
                 // MediaCapture video carries no alpha plane — the OS fills 255.
-                var frame = new VideoFrame(bitmap.PixelWidth, bitmap.PixelHeight, pixels)
+                var videoFrame = new VideoFrame(bitmap.PixelWidth, bitmap.PixelHeight, pixels)
                     { IsOpaque = true, Epoch = ++_epoch };
                 
                 // Diagnostic: Log frame properties for compositor debugging
                 if ((now - _lastAlphaProbe).TotalSeconds >= 5.0)
                 {
-                    AppLog.Write($"Webcam frame emit: {frame.Width}x{frame.Height}, IsOpaque={frame.IsOpaque}, Epoch={frame.Epoch}");
+                    AppLog.Write($"Webcam frame emit: {videoFrame.Width}x{videoFrame.Height}, IsOpaque={videoFrame.IsOpaque}, Epoch={videoFrame.Epoch}");
                 }
                 
-                FrameAvailable?.Invoke(frame);
+                FrameAvailable?.Invoke(videoFrame);
             }
         }
         catch (Exception ex)