fix: match terminal toggle button size with sidebar and review toggles

packages/app/src/components/session/session-header.tsx

@@ -212,7 +212,7 @@ export function SessionHeader() {
                 >
                   <Button
                     variant="ghost"
-                    class="group/terminal-toggle size-8 rounded-md"
+                    class="group/terminal-toggle size-6 p-0"
                     onClick={() => view().terminal.toggle()}
                   >
                     <div class="relative flex items-center justify-center size-4 [&>*]:absolute [&>*]:inset-0">