fix(backup): log missing db config instead of raising

- Use module logger in backup/db.py
- Skip db dump when no databases.csv entry is present
- Apply black/formatting cleanup across backup/restore/tests

https://chatgpt.com/share/69519d45-b0dc-800f-acb6-6fb8504e9b46

src/baudolo/backup/docker.py

@@ -37,7 +37,9 @@ def change_containers_status(containers: list[str], status: str) -> None:
 def docker_volume_exists(volume: str) -> bool:
     # Avoid throwing exceptions for exists checks.
     try:
-        execute_shell_command(f"docker volume inspect {volume} >/dev/null 2>&1 && echo OK")
+        execute_shell_command(
+            f"docker volume inspect {volume} >/dev/null 2>&1 && echo OK"
+        )
         return True
     except Exception:
         return False