fix(lint): resolve pyright and pylint issues in provider/backend changes

- Remove unused Bottle import from docker/backend.py (pyright)
- Suppress wrong-import-position on circular-import-avoiding
  deferred imports in backend/__init__.py (pylint C0413)
- Add encoding="utf-8" to read_text() in smolmachines provision
  test (pylint W1514)
- Suppress consider-using-with on TemporaryDirectory setUp pattern
  in both provision test files (pylint R1732)

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

tests/unit/test_docker_provision_git_user.py

@@ -120,7 +120,7 @@ def _git_config_exec_calls(bottle: MagicMock) -> list[tuple[str, str]]:
 
 class TestProvisionGitUser(unittest.TestCase):
     def setUp(self):
-        self._tmp = tempfile.TemporaryDirectory(prefix="cb-prov-git-user.")
+        self._tmp = tempfile.TemporaryDirectory(prefix="cb-prov-git-user.")  # pylint: disable=consider-using-with
         self.stage = Path(self._tmp.name)
 
     def tearDown(self):