fix: open a list mail without mounting every pane before it #67

The tap fix makes a notification open a single page, so the viewer no
longer needs to render up to the opened index. That setting mounted
about N mail panes on every list open, on iOS too. Also drop the
onScrollToIndexFailed handler, which FlatList never calls when
getItemLayout is set.

src/screens/EmailThreadScreen.tsx

@@ -772,17 +772,12 @@ function EmailViewer({ route, navigation }: Props) {
             initialScrollIndex={initialIndexRef.current}
             getItemLayout={(_, index) => ({ length: windowWidth, offset: windowWidth * index, index })}
             windowSize={3}
-            initialNumToRender={Math.max(initialIndexRef.current + 1, 1)}
+            initialNumToRender={1}
             maxToRenderPerBatch={2}
             removeClippedSubviews
             scrollEnabled={!pagerLocked && kbObstruction === 0}
             onScrollBeginDrag={releaseNeighbours}
             onMomentumScrollEnd={onMomentumEnd}
-            onScrollToIndexFailed={(info) => {
-              setTimeout(() => {
-                listRef.current?.scrollToOffset({ offset: info.index * windowWidth, animated: false });
-              }, 50);
-            }}
             renderItem={({ item, index }) => (
               <View style={{ width: windowWidth }}>
                 <EmailPane