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/schemas.py

@@ -37,6 +37,7 @@ class ChatAttachmentRead(BaseModel):
     id: int
     message_id: int
     sender_id: int
+    message_type: str
     message_created_at: datetime
     file_url: str
     file_type: str