🎨 fix(theme): align UI controls with global radius tokens

Remove hard-coded and capped border radius overrides so shared controls and feature actions consistently follow the active theme radius.

- Replace fixed radius utilities with semantic theme-aware radius tokens
- Remove redundant `rounded-full` and pixel-based overrides from header, toolbar, Playground, and utility actions
- Drop unused `StatusBadge` rounded prop usage
- Keep existing component behavior intact while improving global theme consistency

web/default/src/components/ai-elements/prompt-input.tsx

@@ -429,7 +429,7 @@ export type PromptInputProps = Omit<
   ) => void | Promise<void>
   /**
    * Optional className applied to the inner InputGroup wrapper
-   * (useful for customizing rounded corners, e.g., rounded-[20px]).
+   * (useful for layout or semantic radius utilities such as rounded-xl).
    */
   groupClassName?: string
 }