Feat(webapp): animated resizable panel (#3319)

This is a small improvement mainly with the UI Skills file:

- Animate open and close the Resizable panels
- Uses the built in animation hooks from react-window-splitter
- Includes a global variable for the animation easing and timing for
consistency


https://github.com/user-attachments/assets/50ed0019-ed12-4e08-b95c-7c6d1fe5bac0