Harden player view detach and time-update gate heal from #957

Guard the deinit detach by superview so a container whose render view
was stolen by a newer, not-yet-windowed container cannot rip the shared
view out of it. Narrow the loading-gate heal to .ready only: the old
video still playing during the details/streams fetch can emit .playing,
which would open the gate to stale time updates and break the
stale-error suppression in play()'s catch.

Yattee/Views/Player/MPVRenderViewRepresentable.swift

@@ -91,7 +91,11 @@ private class MPVContainerView: UIView {
             // deallocating container: otherwise SwiftUI keeps reconciling a
             // half-alive view and spins the main-thread trait update loop (100%
             // CPU hang when opening a settings detail during playback, issue #956).
-            playerView.removeFromSuperview()
+            // Guard by superview: currentPlayerView is a stale weak ref when another
+            // (not yet windowed) container has stolen the view — don't rip it out.
+            if playerView.superview === self {
+                playerView.removeFromSuperview()
+            }
         }
     }