Add setting to toggle scale grid visibility (#2838)

* Add a setting for showScaleGrid

* Fix up setting persistence, move under modeling

* Make the setting actually do something

* the lamest fmt I've seen in a while

* Fix clippy warnings

* Add snapshot tests for grid (first time using Playwright masks)

* A snapshot a day keeps the bugs away! 📷🐛 (OS: ubuntu)

* Re-run CI after new screenshots added

---------

Co-authored-by: Jess Frazelle <jessfraz@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

src/components/AppHeader.tsx

@@ -26,6 +26,7 @@ export const AppHeader = ({
 
   return (
     <header
+      id="app-header"
       className={
         'w-full grid ' +
         styles.header +