fix(mobile): anchor chat history below paging header

mobile/src/session/MobileNativeChatView.test.ts

@@ -236,6 +236,7 @@ describe('MobileNativeChatView', () => {
       await update({ messages: [current], hasMore: true, loadingEarlier: true })
       await update({ messages: [older, current], hasMore: false, loadingEarlier: false })
       const list = renderer!.root.find((node) => node.type === 'FlatList')
+      expect(list.props.maintainVisibleContentPosition).toEqual({ minIndexForVisible: 1 })
       act(() => list.props.onContentSizeChange())
       await act(async () => vi.runAllTimersAsync())
 

mobile/src/session/MobileNativeChatView.tsx

@@ -303,9 +303,8 @@ export function MobileNativeChatView({
               contentContainerStyle={styles.listContent}
               onScroll={onScroll}
               scrollEventThrottle={32}
-              // Anchor the viewport to the first visible row so a loadEarlier
-              // prepend grows the list upward instead of jumping the reader.
-              maintainVisibleContentPosition={{ minIndexForVisible: 0 }}
+              // Skip the load-earlier header so the first visible message stays anchored.
+              maintainVisibleContentPosition={{ minIndexForVisible: 1 }}
               onContentSizeChange={() => {
                 if (data.length > 0 && atBottom && !keepHistoryPosition) {
                   listRef.current?.scrollToEnd({ animated: false })