Replace UniqueKey-based row refresh with ValueNotifier signal so rows
reload data in-place without being destroyed/recreated. Only invalidate
home cache when connecting to a different server (not on routine
reconnects after backgrounding). Cache row height to prevent size jumps
caused by the bottom nav bar toggling on connect/disconnect.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>