feat(tabs): add useBottomTabBarHeight for native bottom tabs

[zibs]

Description

This PR introduces an experimental API to read native bottom tab bar height from JS in react-native-screens.

What

• Adds useBottomTabBarHeight and BottomTabBarHeightContext for native bottom tabs.
• Adds native event plumbing (onTabBarHeightChange) on both Android and iOS.

Why

• Native bottom tabs render outside the JS layout tree, so tab bar height wasn’t accessible in screen layout
  code.
• This enables reliable content offset/layout behavior and aligns with common migration expectations.

Relates to #3616 and for react-navigation: react-navigation/react-navigation#12949

Changes

• Added onTabBarHeightChange to BottomTabsNativeComponent spec.
• Added Android tab bar height event emission:
  • TabsHost
  • TabsHostEventEmitter
  • TabsHostViewManager
  • new event type TabsHostTabBarHeightChangeEvent
  • RNSBottomTabsHostEventEmitter
  • RNSBottomTabsHostComponentView / manager event exposure
• Exported new API:
  • useBottomTabBarHeight
  • updated public exports in src/index.tsx and src/types.tsx
• Added verification updates in FabricExample:
  • e2e assertion for ready tab bar height state
  • visible test UI showing height/state
  • Android-only Tab3 content bottom offset using the new hook
• Fixed Android compile regression:
  • added missing ViewGroup import in ScreenStackHeaderConfig.kt
• Updated Swift lint helper:
  • excludes generated iOS build directories to avoid formatting noise

Before & after - visual documentation

without reading tab bar height, content is covered

**after reading tab bar height, we can offset content **

Test plan

Tested files:

• apps/src/tests/issue-tests/TestBottomTabs/components/TabContentView.tsx
• apps/src/tests/issue-tests/TestBottomTabs/tabs/Tab3.tsx

Commands run:

• npm run lint
• ./gradlew :react-native-screens:compileDebugKotlin (from FabricExample/android)

Manual verification:

1. Launch FabricExample.
2. Go to Issue Tests -> TestBottomTabs.
3. Confirm first tab shows ready and a non-zero tab bar height.
4. On Android, open Tab3 and verify bottom content is offset above tab bar using hook value.

Minimal usage example:

import { Platform } from 'react-native';
import { useBottomTabBarHeight } from 'react-native-screens';

function ScreenContent() {
const tabBarHeight = useBottomTabBarHeight();
const bottomPadding = Platform.OS === 'android' ? tabBarHeight : 0;
// apply bottomPadding to content container
}

Checklist

• Included code example that can be used to test this change.
• Updated / created local changelog entries in relevant test files.
• For visual changes, included screenshots / GIFs / recordings documenting the change.
• For API changes, updated relevant public types.
• Ensured that CI passes