feat: realtime sync, settings UX and chat list improvements

- add chat_updated realtime event and dynamic chat subscriptions

- auto-join invite links in web app

- implement Telegram-like settings panel (general/notifications/privacy)

- add browser notification preferences and keyboard send mode

- improve chat list with last message preview/time and online badge

- rework chat members UI with context actions and role crowns

app/media/service.py

@@ -157,6 +157,7 @@ async def list_attachments_for_chat(
             id=attachment.id,
             message_id=attachment.message_id,
             sender_id=message.sender_id,
+            message_type=message.type.value if hasattr(message.type, "value") else str(message.type),
             message_created_at=message.created_at,
             file_url=attachment.file_url,
             file_type=attachment.file_type,