test(launch-prompt): keep the cmd launch-file path case to what the piped harness can carry

The Windows CI harness pipes the typed line into cmd, which decodes it in its
startup code page whatever chcp says, so accents and CJK in the home folder
arrived garbled while cmd split the line into the right two arguments. The
case keeps the apostrophe, the space and the % pair, which are what cmd's
quoting has to survive; a non-ASCII path in a real cmd pane is not measured.

src/shared/cmd-startup-arg-quoting.win32.test.ts

@@ -100,8 +100,10 @@ describeOnWindows('cmd launch-line prompt quoting', () => {
     }
   })
 
-  it('names a launch file under a home with an apostrophe, accents, CJK and `%`', async () => {
-    const home = join(dir, "O'Brien José 张伟 100%")
+  // Why ASCII only: this harness decodes piped input in cmd's startup code page (see the corpus
+  // case above), so accents and CJK in the path arrive garbled here though cmd split it right.
+  it('names a launch file under a home with an apostrophe, a space and `%`', async () => {
+    const home = join(dir, "O'Brien Smith 100%")
     mkdirSync(home)
     const plan = planLaunchForTest({
       agent: 'claude',