feat: complete tree shell cutover and regression coverage

wolai-frontend/src/components/sidebar/file-tree.tsx

@@ -134,6 +134,18 @@ export function FileTree({
         return (
           <div
             key={row.rowId}
+            data-testid={
+              row.kind === "doc"
+                ? "filetree-doc-row"
+                : row.kind === "index"
+                  ? "filetree-index-row"
+                  : row.kind === "asset-folder"
+                    ? "filetree-asset-folder-row"
+                    : "filetree-asset-row"
+            }
+            data-row-id={row.rowId}
+            data-row-kind={row.kind}
+            data-doc-id={row.docId}
             className={cn(
               baseClass,
               active && activeClass,
@@ -227,6 +239,7 @@ export function FileTree({
                   <button
                     type="button"
                     aria-label="展开或折叠"
+                    data-testid="filetree-toggle"
                     onClick={(event) => {
                       event.stopPropagation();
                       onToggleExpand(row.docId);
@@ -248,6 +261,7 @@ export function FileTree({
                 <button
                   type="button"
                   aria-label="新建子页面"
+                  data-testid="filetree-create"
                   onClick={(event) => {
                     event.stopPropagation();
                     onCreateChild(row.docId);
@@ -269,6 +283,7 @@ export function FileTree({
                   <button
                     type="button"
                     aria-label="展开或折叠"
+                    data-testid="filetree-toggle"
                     onClick={(event) => {
                       event.stopPropagation();
                       onToggleAssetFolderExpand?.(row.asset.id);