Add return code to `qmk userspace-doctor` (#25775)

lib/python/qmk/cli/userspace/doctor.py

@@ -2,10 +2,12 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 from milc import cli
 
-from qmk.constants import QMK_FIRMWARE
+from qmk.constants import QMK_FIRMWARE, HAS_QMK_USERSPACE
 from qmk.cli.doctor.main import userspace_tests
 
 
 @cli.subcommand('Checks userspace configuration.')
 def userspace_doctor(cli):
     userspace_tests(QMK_FIRMWARE)
+
+    return 0 if HAS_QMK_USERSPACE else 1