统一报销错误提示无障碍样式（08-30-b2-submit-error-ocr-fallback）

client/src/pages/reimbursement-detail/ReimbursementActions.tsx

@@ -40,8 +40,10 @@ export function ReimbursementActions({
     <div className="space-y-4">
       {actionError ? (
         <p
-          className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-600"
+          className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-700"
           data-testid="reimbursement-action-error"
+          role="alert"
+          aria-live="assertive"
         >
           {actionError}
         </p>