Fresh pip installs pull supermemory 3.50, which renamed MemoryAddResponse
and MemoryGetResponse and moved document creation to client.add(). The
package failed to import and memory writes used a removed API surface.
Migrate tools and middleware to AddResponse/DocumentGetResponse and
client.add(), pin supermemory>=3.50.0 (Python 3.9+), and add import
compatibility regression tests.
Fixes#1235
