Address beta feedback

* Use signal blue for search box focus outline
* Reduce debounce for draft saves
* Be less aggressive in our scrolling corrections
* Lightbox: Ensure that a tall image is still fully visible
* Fix spell checking after Electron API breaking changes
* Fix link preview image generation
* Message highlight: Move to border in signal blue

ts/components/Lightbox.tsx

@@ -56,6 +56,8 @@ const styles = {
     paddingLeft: 40,
     paddingRight: 40,
     paddingBottom: 0,
+    // To ensure that a large image doesn't overflow the flex layout
+    minHeight: '50px',
   } as React.CSSProperties,
   objectContainer: {
     position: 'relative',