Tweak text selection BGs (#3181)

Fixes #3179 

Message:
<img width="491" height="124" alt="image"
src="https://github.com/user-attachments/assets/3ac373bc-e422-4cf7-83f0-2d1d470f3971"
/>
<img width="485" height="116" alt="image"
src="https://github.com/user-attachments/assets/8006e0b0-56d4-402c-bd7f-961105546095"
/>

Terminal:
<img width="678" height="261" alt="image"
src="https://github.com/user-attachments/assets/2bf46c10-269a-4c71-977a-0b5b4d06667d"
/>
<img width="669" height="257" alt="image"
src="https://github.com/user-attachments/assets/e950d2d0-ee06-44d0-a707-c78f29aac24a"
/>

Author: benjaminleonard

app/components/Terminal.tsx

@@ -38,6 +38,7 @@ function getTheme(): ITerminalOptions['theme'] {
     brightCyan: style.getPropertyValue('--content-accent'),
     magenta: style.getPropertyValue('--content-accent-alt-secondary'),
     brightMagenta: style.getPropertyValue('--content-accent-alt'),
+    selectionBackground: style.getPropertyValue('--surface-accent'),
     cursor: style.getPropertyValue('--content-default'),
     cursorAccent: style.getPropertyValue('--surface-default'),
   }

app/ui/styles/index.css

@@ -75,11 +75,11 @@
 
 ::-moz-selection {
   /* Code for Firefox */
-  @apply text-accent bg-accent;
+  @apply bg-accent-inverse/30;
 }
 
 ::selection {
-  @apply text-accent bg-accent;
+  @apply bg-accent-inverse/30;
 }
 
 @custom-variant selected {