iOS: optimize chapters list to render at current chapter instantly

- Added custom init to ChaptersListSheet that sets scrollPosition state before view appears
- Removed onAppear scroll position update (now set in init)
- List renders directly at current chapter position without any scroll animation
- Better performance for books with 1000+ chapters (no initial render + animate delay)

ios/LibNovel/LibNovel/Views/Player/PlayerViews.swift

@@ -759,6 +759,16 @@ struct ChaptersListSheet: View {
     let onChapterSelect: (Int) -> Void
     
     @Environment(\.dismiss) private var dismiss
+    
+    // Initialize scroll position to current chapter immediately (before view appears)
+    init(chapters: [ChapterIndexBrief], currentChapter: Int, onChapterSelect: @escaping (Int) -> Void) {
+        self.chapters = chapters
+        self.currentChapter = currentChapter
+        self.onChapterSelect = onChapterSelect
+        // Set initial scroll position state before view renders
+        _scrollPosition = State(initialValue: currentChapter)
+    }
+    
     @State private var scrollPosition: Int?
     
     var body: some View {
@@ -815,10 +825,6 @@ struct ChaptersListSheet: View {
             }
             .listStyle(.plain)
             .scrollPosition(id: $scrollPosition, anchor: .center)
-            .onAppear {
-                // Set initial scroll position without animation
-                scrollPosition = currentChapter
-            }
             .navigationTitle("Chapters")
             .navigationBarTitleDisplayMode(.inline)
             .toolbar {