revert(core): restore intentional ReadFolder display behavior (result: null)

packages/core/src/tools/ls.ts

@@ -288,14 +288,6 @@ class LSToolInvocation extends BaseToolInvocation<LSToolParams, ToolResult> {
           name: LS_DISPLAY_NAME,
           description: this.getDescription(),
           resultSummary: displayMessage,
-          result: {
-            type: 'text',
-            text: entries
-              .map(
-                (entry) => `${entry.isDirectory ? '[DIR] ' : ''}${entry.name}`,
-              )
-              .join('\n'),
-          },
         },
         returnDisplay: {
           summary: displayMessage,