feat: add onPress to tap the anchor while long-press opens the menu

[zcmgyu]

The problem

Right now, if you set shouldOpenOnLongPress, the menu opens on long-press, but a normal tap on the anchor does nothing. There's no way to handle it.

That makes a very common mobile pattern impossible:

▎ Tap a row to open it, long-press it for a context menu (rename, delete, …).

On iOS the anchor is a native UIButton, so it quietly swallows the tap and never tells JS about it.

The fix

A new onPress prop. When shouldOpenOnLongPress is on:

• Tap → fires onPress
• Long-press → opens the menu (unchanged)

So the anchor is now both tappable and long-pressable.

<MenuView
  shouldOpenOnLongPress
  onPress={() => openItem(item)}        // 👈 tap
  onPressAction={({ nativeEvent }) => {  // long-press → menu item chosen
    if (nativeEvent.event === 'delete') deleteItem(item)
  }}
  actions={[{ id: 'delete', title: 'Delete', attributes: { destructive: true } }]}
>
  <Row item={item} />
</MenuView>

How it works

The native side reports the anchor tap through the existing onPressAction channel using a reserved id ("rnmenu:onPress"), and index.tsx turns that into the public onPress callback:

• iOS: UIButton's touchUpInside (only when the menu isn't the primary tap action), plus the iOS <14 action-sheet tap path
• Android: onSingleTapUp while in long-press mode

No breaking changes

onPress only fires in long-press mode. Regular tap-to-open menus (shouldOpenOnLongPress={false}) behave exactly as before.

Changes

• New onPress prop (types + JS)
• iOS: MenuViewImplementation.swift, ActionSheetView.swift
• Android: MenuView.kt
• Docs: README