Fix macOS permanent black video after player collapse/expand cycles

In separate-window mode, hide() keeps the ordered-out window's SwiftUI
hierarchy alive (nilling contentViewController crashes AVKit), and its
updateNSView unconditionally re-attached the shared MPVOGLView -
stealing it into a window CoreAnimation never composites. The layer's
silent skip-render fallback then consumed every frame flag, so video
stayed black (climbing vo drops) until app restart.

- Decline stealing the shared view from a visible container into a
  non-visible one; owner-initiated transfers bypass the guard
- Only transfer to containers in visible windows or the window still
  tracked by ExpandedPlayerWindowManager; park the view otherwise and
  reclaim it when a container gains a window
- Log skip-render frame consumption (rate-limited) and track render
  health counters (draws/skips/dropped draws)
- Add a watchdog to the playback stats task that detects a stalled
  video output and re-attaches the view to a visible container
- Don't mount player layouts during zero-size layout passes

Yattee/Views/Player/ExpandedPlayerSheet.swift

@@ -303,7 +303,14 @@ struct ExpandedPlayerSheet: View {
                 Color.black.ignoresSafeArea(edges: .bottom)
 
                 #if os(iOS) || os(macOS)
-                if wideScreen {
+                if geometry.size.width <= 0 || geometry.size.height <= 0 {
+                    // Transient zero-size layout pass (e.g. the deferred macOS
+                    // player window before its first real layout). Don't mount
+                    // either layout branch — a branch mounted here would grab
+                    // the shared render view for one frame and immediately hand
+                    // it off when the real size picks the other branch.
+                    Color.black.ignoresSafeArea(.all)
+                } else if wideScreen {
                     if let video = playerState?.currentVideo {
                         // Widescreen layout with floating panel
                         // Must ignore safe area to get full screen geometry