refactor: use ably/react hooks in React Native push guide

- Wrap app in AblyProvider + ChannelProvider
- Split App into App (providers) and PushScreen (hooks)
- Replace manual useEffect channel subscription with useChannel
- Replace module-scope realtime client with useAbly() in PushScreen
- Update ably channels publish CLI to ably push publish --channel
- Remove scrollViewRef auto-scroll for brevity
- Rename appendLog to log

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: maratal

src/data/nav/pubsub.ts

@@ -271,6 +271,7 @@ export default {
             {
               name: 'React Native',
               link: '/docs/push/getting-started/react-native',
+              languages: ['javascript'],
             },
           ],
         },