style(chat): unify composer toolbar heights and declutter slash-command modal

- Composer: give the permission-mode and token-usage buttons a fixed
  h-8 so every bottom-toolbar control shares one height
- CommandResultModal: replace the blue gradient header (gradient fill,
  glow blobs, blue eyebrow + icon chip) with a clean neutral header on
  popover/muted tokens

src/components/chat/view/subcomponents/ChatComposer.tsx

@@ -331,7 +331,7 @@ export default function ChatComposer({
             <button
               type="button"
               onClick={onModeSwitch}
-              className={`rounded-lg border p-2 text-xs font-medium transition-all duration-200 sm:px-2.5 sm:py-1 ${
+              className={`inline-flex h-8 items-center rounded-lg border px-2 text-xs font-medium transition-all duration-200 sm:px-2.5 ${
                 permissionMode === 'default'
                   ? 'border-border/60 bg-muted/50 text-muted-foreground hover:bg-muted'
                   : permissionMode === 'acceptEdits'