AppTest

This release introduces lazy loading for st.dataframe, an icon parameter for st.metric, and background refresh for st.cache_data and st.cache_resource. It also includes several bug fixes and improvements to existing widgets.

This release switches the default server to Starlette, removes Tornado, and introduces several new features like animated loading text (:shimmer[]) and the st.bottom container. Numerous bug fixes address compatibility with pandas 3.0+ and improve widget behavior.