Clarify MinIO get() error semantics to match Redis behavior.

Return None only for missing objects and re-raise other S3 and network failures so callers can distinguish not-found from real errors.

Co-authored-by: Cursor <[email protected]>

python_repositories/interfaces/object_repository_interface.py

@@ -9,7 +9,11 @@ class ObjectRepositoryInterface(ABC):
 
     @abstractmethod
     def get(self, object_name: str) -> BytesIO | None:
-        """Get an object by name."""
+        """Get an object by name.
+
+        Returns None when the object does not exist. Raises ConnectionError when
+        not connected. Other backend errors propagate to the caller.
+        """
         ...
 
     @abstractmethod