Keep the macOS PiP video sized to the PiP window

Once PiP starts the player's container view collapses to zero, and
AVSampleBufferDisplayLayer stops laying out its internal video sublayer,
so resizing the PiP window left the video at its starting size in the
bottom-left corner. Force the layer's layout after each resize.

Yattee/Services/Player/MPV/MPVPiPBridge.swift

@@ -1016,6 +1016,19 @@ extension MPVPiPBridge {
         LoggingService.shared.debug("MPVPiPBridge: Restored \(count) hidden PiP views", category: .mpv)
     }
 
+    /// AVSampleBufferDisplayLayer lays out its internal video container
+    /// sublayer only during a layout pass of its host window. Once PiP starts
+    /// our container view collapses to zero and that pass stops reaching the
+    /// layer, so the video in the PiP window kept the size it had when PiP
+    /// started while the window around it was resized. Lay it out ourselves.
+    private func syncSampleBufferSublayers() {
+        CATransaction.begin()
+        CATransaction.setDisableActions(true)
+        sampleBufferLayer.setNeedsLayout()
+        sampleBufferLayer.layoutIfNeeded()
+        CATransaction.commit()
+    }
+
     /// Update the sample buffer layer's frame to match the PiP window size.
     private func updateLayerFrameToMatchPiPWindow() {
         // Try to find the PiP window
@@ -1043,6 +1056,7 @@ extension MPVPiPBridge {
                 sampleBufferLayer.frame = newFrame
                 CATransaction.commit()
             }
+            syncSampleBufferSublayers()
         } else {
             // Fallback: try to match superlayer
             guard let superlayer = sampleBufferLayer.superlayer else { return }