Improvements to editing with Assist

Retool improved Assist's ability to reason about and plan layout changes for large and complex apps. This change has the following impacts:

• Improves the quality of layouts when editing medium to large apps. Assist is now better at formatting the spacing and alignment of components.
• Improves latency when making large edits to UI layout. For example, one layout change that previously took 5 minutes now takes under 1.5 minutes.
• Improves support for adding header frames.

This change is available on Retool Cloud and will be available in subsequent releases of self-hosted Retool.