fix(a11y): use KUI Button instead of native button for clickable regions

Wrapping content in a raw <button> bypasses KUI's focus/styling tokens.
Use the KUI Button primitive instead:
- ReportTraceModal: trace-card clickable -> <Button kind=tertiary> (copy
  button stays a sibling, no nesting).
- FileTag: no-file clickable -> <Button kind=tertiary>.

Signed-off-by: mschwab <mschwab@nvidia.com>

Author: marcusds

web/packages/studio/src/components/FileTag/index.tsx

@@ -1,7 +1,7 @@
 // SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-import { Flex, Tag, TagProps } from '@nvidia/foundations-react-core';
+import { Button, Flex, Tag, TagProps } from '@nvidia/foundations-react-core';
 import { CircleCheck, X, RefreshCw, CircleAlert as ErrorIcon } from 'lucide-react';
 import { FC, ReactNode, MouseEventHandler } from 'react';
 
@@ -64,9 +64,9 @@ export const FileTag: FC<FileTagProps> = ({
           {onClick && <X />}
         </Tag>
       ) : onNoFileClick ? (
-        <button type="button" onClick={onNoFileClick} className="cursor-pointer">
+        <Button kind="tertiary" onClick={onNoFileClick} className="h-auto p-0">
           {missingFileNameChip}
-        </button>
+        </Button>
       ) : (
         <div>{missingFileNameChip}</div>
       )}

web/packages/studio/src/components/ReportTraceModal/index.tsx

@@ -229,9 +229,9 @@ export const ReportTraceModal = ({ open, onClose }: ReportTraceModalProps) => {
                     align="center"
                     className="p-3 bg-surface-raised rounded-md border border-base"
                   >
-                    <button
-                      type="button"
-                      className="flex-1 text-left cursor-pointer appearance-none focus:outline-none focus:ring-2 focus:ring-brand"
+                    <Button
+                      kind="tertiary"
+                      className="h-auto flex-1 justify-start p-0 text-left"
                       aria-label={`View details for ${trace.message}`}
                       onClick={() => handleViewDetails(trace)}
                     >
@@ -252,7 +252,7 @@ export const ReportTraceModal = ({ open, onClose }: ReportTraceModalProps) => {
                           </Text>
                         )}
                       </Stack>
-                    </button>
+                    </Button>
                     <Button kind="tertiary" size="small" onClick={() => handleCopyTrace(trace)}>
                       <Copy />
                     </Button>