fix: PinInput separator — flex center on the separator div itself

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/base/pin-input/pin-input.tsx

@@ -115,7 +115,7 @@ const FakeCaret = ({ size = "md" }: { size?: "sm" | "md" | "lg" }) => {
 
 const Separator = (props: ComponentPropsWithRef<"p">) => {
     return (
-        <div role="separator" {...props} className={cx("text-center text-display-xl font-medium text-placeholder_subtle", props.className)}>
+        <div role="separator" {...props} className={cx("flex items-center justify-center text-display-xl font-medium text-placeholder_subtle", props.className)}>
             -
         </div>
     );