fix: tab bar collapses during auto-scroll

tabBarMinimizeBehavior needs scrollViewWillBeginDragging to recognize
a scroll session. Now ScrollViewDriver calls it on the original
delegate when auto-scroll starts, and scrollViewDidEndDragging +
scrollViewDidEndDecelerating when it stops.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ios/Platform/Platform/Features/Reader/Views/ScrollViewDriver.swift

@@ -78,11 +78,13 @@ struct ScrollViewDriver: UIViewRepresentable {
         }
 
         func startScrolling(in view: UIView) {
-            // Re-find scroll view if needed
             if scrollView == nil {
                 findScrollView(from: view)
             }
-            guard scrollView != nil else { return }
+            guard let sv = scrollView else { return }
+
+            // Signal scroll start — triggers tab bar minimize
+            originalDelegate?.scrollViewWillBeginDragging?(sv)
 
             let link = CADisplayLink(target: self, selector: #selector(tick))
             link.preferredFrameRateRange = CAFrameRateRange(minimum: 30, maximum: 60)
@@ -93,6 +95,12 @@ struct ScrollViewDriver: UIViewRepresentable {
         func stopScrolling() {
             displayLink?.invalidate()
             displayLink = nil
+
+            // Signal scroll end — lets tab bar reappear
+            if let sv = scrollView {
+                originalDelegate?.scrollViewDidEndDragging?(sv, willDecelerate: false)
+                originalDelegate?.scrollViewDidEndDecelerating?(sv)
+            }
         }
 
         @objc private func tick(_ link: CADisplayLink) {