fix: add missing type annotations and remove unused variables in new tests

Pyright flagged three inner class `status` methods missing a type
annotation on the `quiet` parameter, and two unused variables
(`written`, `real_status`) left over from an earlier draft of
test_docker_quiet_true_suppresses_stderr.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_backend_setup.py

@@ -342,8 +342,6 @@ class TestBackendStatusQuiet(unittest.TestCase):
     def test_docker_quiet_true_suppresses_stderr(self):
         import io as _io
         from bot_bottle.backend.docker.backend import DockerBottleBackend
-        written = []
-        real_status = dk.status
 
         def _loud_status():
             import sys