Don't animate the video info carousel into place when it first opens

On iPhone Duo the page first lays out at full width, then narrows for the
status column, and the width-change re-snap animated from the first card
to the tapped one. Only animate the re-snap when the current card was
already on screen at the old width.

Yattee/Views/Video/VideoInfoView.swift

@@ -41,6 +41,8 @@ struct VideoInfoView: View {
     #if os(iOS)
     @State private var carouselScrollPosition: Int?
     @State private var clearsCarouselPositionWhenIdle = false
+    /// Last scroll offset, kept in a box so tracking it doesn't re-render the view every frame
+    @State private var carouselOffset = CarouselOffsetBox()
     #endif
     
     // Continuation loading state
@@ -1036,6 +1038,9 @@ struct VideoInfoView: View {
             .frame(width: cardWidth)
             .scrollTargetBehavior(.viewAligned(limitBehavior: .alwaysByOne))
             .scrollPosition(id: $carouselScrollPosition)
+            .onScrollGeometryChange(for: CGFloat.self) { $0.contentOffset.x } action: { _, new in
+                carouselOffset.value = new
+            }
             .onScrollPhaseChange { oldPhase, newPhase in
                 if newPhase == .interacting {
                     clearsCarouselPositionWhenIdle = false
@@ -1058,18 +1063,23 @@ struct VideoInfoView: View {
                     proxy.scrollTo(newValue, anchor: .center)
                 }
             }
-            .onChange(of: cardWidth) { _, _ in
+            .onChange(of: cardWidth) { oldW, _ in
                 // A width change (iPhone Duo unfold, rotation, split resize) keeps
                 // the old point offset, leaving the cards misaligned. Re-snap to the
                 // current card (setting the same id is a no-op, hence the nil hop).
                 // The LazyHStack keeps re-applying a programmatic position while it
                 // realizes cards, which stopped the next swipe halfway between two
                 // cards, so the position is cleared again once the re-snap settles.
+                // Only animate when the current card was on screen at the old width
+                // (unfold, rotation). The first layout of a page opened on a later
+                // card also arrives as a width change (iPhone Duo status column
+                // inset), and animating that scrolls visibly from the first card.
                 guard let index = currentVideoIndex else { return }
+                let wasShowingCard = abs(carouselOffset.value - CGFloat(index) * (oldW + carouselSpacing)) < 1
                 carouselScrollPosition = nil
                 DispatchQueue.main.async {
                     clearsCarouselPositionWhenIdle = true
-                    withAnimation(.linear(duration: 0.15)) {
+                    withAnimation(wasShowingCard ? .linear(duration: 0.15) : nil) {
                         carouselScrollPosition = index
                     }
                 }
@@ -2873,3 +2883,9 @@ private struct VideoInfoScrollOffsetModifier: ViewModifier {
             .videoQueueContext(.init(video: .preview, queueSource: .manual, sourceLabel: "Manual", videoList: [.preview, .livePreview], videoIndex: 0, startTime: 0, loadMoreVideos: .none))
     }
 }
+
+#if os(iOS)
+private final class CarouselOffsetBox {
+    var value: CGFloat = 0
+}
+#endif