test(issue31): the spelling test's holder keeps the uuid in its argv (Issue #31, Mac R2)

macOS /bin/sh (bash 3.2) execs the lone `sleep 120` of `sh -c "sleep 120" <uuid>`,
so the uuid left the process list and both [upper] and [mixed] failed on the Mac.
A Python holder keeps the uuid in argv, like _holder() in test_issue10_13_purge.py.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VCgu9Fa9iT7TbJUSzdq4Ff

tests/test_issue31_purge_residual.py

@@ -312,7 +312,9 @@ def test_any_spelling_of_the_uuid_is_the_lowercase_session(home, tmp_path, conv,
 
     live.kill()
     live.wait()
-    named = subprocess.Popen(["sh", "-c", "sleep 120", conv])
+    # Not `sh -c "sleep 120" <uuid>`: a shell execs its last simple command
+    # and the uuid would vanish from the process list (macOS /bin/sh).
+    named = subprocess.Popen([sys.executable, "-c", "import time; time.sleep(120)", conv])
     try:
         time.sleep(0.05)
         assert adapter.conversation_in_use(other, ctx) is True, "a command line naming the lowercase id"