1. Chat scroll: add flex flex-col to MobileChatScreen messages wrapper
so MessageList's flex-1 actually works (parent must be flex container)
2. Instance General panel: add fetchInstanceSettings/fetchStreamingLimits
to MobileInstancePanel mount (mirrors desktop InstancePanel useEffect)
3. Friends activity: add Activity tab to mobile FriendsPage showing
friends grouped by activity status (active, online, offline)
Replace inline InstancePanel render with MobileInstancePanel that shows
a navigation list for General, Streaming, Storage, and Users sub-panels.
Each sub-panel pushes onto the mobile screen stack with MobileScreenHeader.
Jannis Braun