feat: add frosted glass feature option

- Add 'Frosted Glass' to design features list in design-scheme.ts
- Implement visual styling for frosted glass feature in ColorSchemeDialog
- Adjust sidebar button margin in Workbench for better spacing

app/components/workbench/Workbench.client.tsx

@@ -388,8 +388,8 @@ export const Workbench = memo(
               <div className="h-full flex flex-col bg-bolt-elements-background-depth-2 border border-bolt-elements-borderColor shadow-sm rounded-lg overflow-hidden">
                 <div className="flex items-center px-3 py-2 border-b border-bolt-elements-borderColor gap-1.5">
                   <button
-                    className={`${showChat ? 'i-ph:sidebar-simple-fill' : 'i-ph:sidebar-simple'} text-lg text-bolt-elements-textSecondary`}
-                    disabled={!canHideChat || isSmallViewport} // expand button is disabled on mobile as it's not needed
+                    className={`${showChat ? 'i-ph:sidebar-simple-fill' : 'i-ph:sidebar-simple'} text-lg text-bolt-elements-textSecondary mr-1`}
+                    disabled={!canHideChat || isSmallViewport}
                     onClick={() => {
                       if (canHideChat) {
                         chatStore.setKey('showChat', !showChat);