fix(tool-str-replace-editor): platform-normalize listing assertion paths

The view listing carries absolute display paths, so the POSIX-style
'node_modules_old/kept.js' substring assertions only match on Linux
(Windows display paths use backslashes). Assert with platform separators
to keep the same check meaningful on Windows; the pre-existing gap is
identical on master.

packages/fs/tool-str-replace-editor/tests/tools.spec.ts

@@ -244,8 +244,10 @@ describe('tool-str-replace-editor', () => {
     expect(listing).not.toContain('too-deep.txt')
     expect(listing).not.toContain('index.js')
     expect(listing).not.toContain('module.pyc')
-    expect(listing).toContain('node_modules_old/kept.js')
-    expect(listing).toContain('__pycache__backup/kept.py')
+    // The listing carries absolute display paths; the POSIX-style substrings
+    // only match on Linux, so assert with platform separators.
+    expect(listing).toContain(join('node_modules_old', 'kept.js'))
+    expect(listing).toContain(join('__pycache__backup', 'kept.py'))
 
     const clipped = await setup({ maxOutputChars: 10 })
     await writeFile(join(clipped.root, 'large.txt'), 'x'.repeat(100))