Replace UIScreen.main with scene-local context

- List row hairlines read displayScale from the SwiftUI environment
- MPV render views take contentScaleFactor from traitCollection and
  re-apply it on UITraitDisplayScale changes
- ExpandedPlayerWindow scales against the presenting view's own height
- MPVPiPBridge sizes the PiP layer from the container view's window
  scene screen (UIScreen.main kept only as a nil-window fallback)
- WideScreenPlayerLayout falls back to the offered geometry size
- Remote control fullscreen state comes from the player sheet's layout
  pass via NavigationCoordinator.isWideScreenLayoutActive instead of
  screen bounds aspect
- Orientation TODOs for Dynamic Island side detection and
  prefersInterfaceOrientationLocked

Yattee/Services/Player/MPV/MPVRenderView.swift

@@ -229,7 +229,10 @@ final class MPVRenderView: UIView {
 
     private func commonInit() {
         backgroundColor = .black
-        contentScaleFactor = UIScreen.main.scale
+        contentScaleFactor = traitCollection.displayScale
+        registerForTraitChanges([UITraitDisplayScale.self]) { (self: MPVRenderView, _) in
+            self.contentScaleFactor = self.traitCollection.displayScale
+        }
 
         // Configure EAGL layer
         // Note: retainedBacking=true is required for glReadPixels to work (PiP frame capture).