InstantPage V2: support nested <details> blocks

A details block nested inside another rendered (title + chevron) but could not
expand: its body is hosted by a fresh InstantPageV2View whose detailsTapped
closure was never wired (only the top-level view's is, by the bubble), so the
nested title's tap hit a nil closure and was dropped. Wire the body view's
detailsTapped to chain through this view's onTitleTapped, which makeItemView
already routes to the owning view's detailsTapped -> the bubble's toggle
handler; this chains up through arbitrary nesting depth.

Also make the bubble's defaultExpanded(forDetailsIndex:) recurse into expanded
bodies so a nested details whose model default is expanded toggles from the
correct state (the flat top-level scan missed nested indices).

Known pre-existing limitation (unchanged): V2 keys expansion state by a flat
DFS index, so expanding a nested details can shift sibling indices.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

submodules/InstantPageUI/Sources/InstantPageRenderer.swift

@@ -1803,6 +1803,13 @@ final class InstantPageV2DetailsView: UIView, InstantPageItemView {
                     self.addSubview(body)
                     self.bodyView = body
                 }
+                // Forward taps on details NESTED inside this body up to the same toggle handler this
+                // view uses: makeItemView wired our onTitleTapped to the owning InstantPageV2View's
+                // detailsTapped, so chaining through onTitleTapped reaches the bubble's toggle handler.
+                // Without this, a nested details' tap hits the body view's nil detailsTapped and is dropped.
+                body.detailsTapped = { [weak self] index in
+                    self?.onTitleTapped?(index)
+                }
                 body.update(layout: innerLayout, theme: theme, animation: animation)
                 body.frame = CGRect(
                     origin: CGPoint(x: 0.0, y: item.titleFrame.maxY),

submodules/TelegramUI/Components/Chat/ChatMessageRichDataBubbleContentNode/Sources/ChatMessageRichDataBubbleContentNode.swift

@@ -164,12 +164,23 @@ public class ChatMessageRichDataBubbleContentNode: ChatMessageBubbleContentNode
 
     private func defaultExpanded(forDetailsIndex index: Int) -> Bool {
         guard let layout = self.currentPageLayout?.layout else { return false }
-        for item in layout.items {
+        func search(_ items: [InstantPageV2LaidOutItem]) -> Bool? {
-            if case let .details(d) = item, d.index == index {
+            for item in items {
-                return d.defaultExpanded
+                if case let .details(d) = item {
+                    if d.index == index {
+                        return d.defaultExpanded
+                    }
+                    // Recurse into an expanded parent's body so NESTED details indices resolve too;
+                    // the flat top-level scan missed them, leaving the toggle's "current state"
+                    // computation wrong for a nested details whose model default is expanded.
+                    if let inner = d.innerLayout, let found = search(inner.items) {
+                        return found
+                    }
+                }
             }
+            return nil
         }
-        return false
+        return search(layout.items) ?? false
     }
 
     required public init?(coder aDecoder: NSCoder) {