* experimental: use TextareaAutosize wrapper with useLayoutEffect to hopefully fix random textarea jankiness
* fix(Textarea): force a resize when placeholder text changes
* style(ScrollToBottom): update styling for scroll button
* style: memoize values and improve side panel toggle states
* refactor(SidePanel): more control for toggle states, new hide panel button, and improve toggle state logic
* chore: hide resizable panel handle on smaller screens
