Don't log missing plugin containers as error when creating network

When the Supervisor network doesn't exist yet and gets created on fresh
startup, the plugin containers (observer, cli, dns, audio) legitimately
don't exist either. The subsequent attach_container_by_name calls are
wrapped in suppress(DockerError), but the DockerError constructor was
passed _LOGGER.error, producing noisy ERROR lines before the exception
was suppressed.

Convert 404 responses from docker.containers.get() into DockerNotFound
(a DockerError subclass) raised without logging, while keeping ERROR-
level logging for any other Docker API failures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

supervisor/docker/network.py

@@ -24,7 +24,7 @@ from ..const import (
     OBSERVER_DOCKER_NAME,
     SUPERVISOR_DOCKER_NAME,
 )
-from ..exceptions import DockerError
+from ..exceptions import DockerError, DockerNotFound
 
 _LOGGER: logging.Logger = logging.getLogger(__name__)
 
@@ -290,6 +290,8 @@ class DockerNetwork:
         try:
             container = await self.docker.containers.get(name)
         except aiodocker.DockerError as err:
+            if err.status == HTTPStatus.NOT_FOUND:
+                raise DockerNotFound(f"Can't find {name}") from err
             raise DockerError(f"Can't find {name}: {err}", _LOGGER.error) from err
 
         if container.id not in self.containers: