test(issue-50): the two new knobs join the #26 table; the herdr box sweeps a late state write

MAM_ONBOARD_WAIT_S (min 1, 600) and MAM_DISPATCH_WAIT_S (min 0, 600) in
test_issue26_ints.INT_KNOBS, which pins every mam_int_knob call. The
real-herdr box's teardown removes its HOME once more after a second:
herdr writes .local/state/herdr/agent-detection a moment after the
server is gone, which left an empty /tmp/mam50-* behind.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/test_issue50_dispatch_herdr.py

@@ -223,6 +223,10 @@ def _teardown(box: Box) -> None:
         except OSError:
             pass
     shutil.rmtree(box.home, ignore_errors=True)
+    # herdr writes its agent-detection state under $HOME/.local/state a moment
+    # after the server is gone: sweep once more
+    time.sleep(1)
+    shutil.rmtree(box.home, ignore_errors=True)
 
 
 @pytest.fixture