feat: reply to chat messages straight from the notification

[GSTJ]

Summary

Chat pushes now have a Reply action you can answer without opening the app, and they land on their own "Messages" channel on Android.

Details

• Dedicated Android notification channel for chat messages, with a localized name (en / pt-BR). The server now tags chat pushes with it.
• Notification category with a text-input Reply action on both platforms, localized ("Reply" / "Responder"). The server tags chat pushes with the matching categoryId (the real expo-server-sdk field name, the docs' categoryIdentifier doesn't exist on the type).
• The reply goes through the same tRPC send-message mutation the chat screen uses, handled by the root-level notification listener, so it works with no chat screen mounted. The swipe screen's separate listener now skips reply responses so nothing double-fires.
• Known expo-notifications limit: replying from a killed app briefly foregrounds the app to deliver the event. Foreground and background replies don't need that.
• Tapping the notification body already deep-linked to the right conversation; verified and left untouched.
• JS-only change, no version bump, so this one can ship over the air.

Testing steps

Needs a real device and a fresh install (Android only registers the new channel on first launch; on a device with an older build, reinstall first).

1. From a second test account, send yourself a chat message with the app in the background.
2. Expand the notification: there should be a Reply button. Type an answer and send it right there. The other account receives it and your phone stays where it was, no chat screen popping up.
3. Force-close the app and reply from the notification again: the app will open briefly (expected), and the message still goes out.
4. Tap the body of a chat notification: the app opens that exact conversation.
5. Android: long-press the notification or check the app's notification settings, chat messages now appear under their own "Messages" category, separate from the rest.