fix: federation avatar colors, cross-instance DMs, and instance persistence

- Fix avatar gradient colors in 7 UI sites by using homeUserId fallback
- Merge remote DM channels in populateFromReady (no longer home-only)
- Remove isHome guards from 8 DM WS event handlers for cross-instance DMs
- Route DM typing events to correct instance origin
- Fix autoConnectAll deleting disconnected instances from localStorage
- Distinguish network errors from auth errors in instance reconnection
- Start WebSocket retry for network-unreachable instances (auto-recovery)
- Add reconnectInstance method and Reconnect button in UI

packages/web/src/components/modals/AddDmMemberModal.tsx

@@ -122,7 +122,7 @@ export function AddDmMemberModal() {
               disabled={isAdding}
               className="w-full flex items-center gap-3 px-3 py-2 rounded-[4px] hover:bg-interactive-hover transition-colors text-left disabled:opacity-50"
             >
-              <Avatar src={user.avatar} name={user.displayName ?? user.username} size={36} status={user.status as any} userId={user.id} />
+              <Avatar src={user.avatar} name={user.displayName ?? user.username} size={36} status={user.status as any} userId={user.homeUserId ?? user.id} />
               <div className="flex-1 min-w-0">
                 <div className="text-[14px] font-medium text-txt-primary truncate">
                   {user.displayName ?? user.username}