Fix macOS black video after re-parenting the shared player view

The player video surface is a single shared MPVOGLView that is re-parented
between the mini-bar container (main window) and the expanded-player sheet
(a separate sheet window). When presenting the sheet, the new container
attaches the shared view before the old mini-bar container tears down, so
the old container's viewWillMove(toSuperview: nil) was ripping the shared
view out of its new home via removeFromSuperview() — leaving it with no
window and a black surface. Symmetric, so it also blanked the mini-bar
preview after collapsing.

Only detach the shared view if it still belongs to the container
(superview === self). Also force a repaint on window reattach so a paused
frame redraws, and extend the onAppear resumeRendering to macOS.

Yattee/Services/Player/MPV/MPVOGLView.swift

@@ -170,6 +170,12 @@ final class MPVOGLView: NSView {
 
             // Update contents scale for new window
             videoLayer?.contentsScale = window.backingScaleFactor
+
+            // Reattaching (e.g. macOS player sheet dismissed via ESC then re-expanded)
+            // detaches this shared view without stopping playback. macOS drawing is
+            // pull-based, so force a redraw to repaint the current frame — otherwise
+            // the layer stays black until MPV emits a new frame (never, if paused).
+            resumeRendering()
         }
     }