run: Use the provided model reference

[doringeman]

This mimics the docker run + docker ps behaviour to display the used (model) reference.

Before:

$ docker model run sha256:354bf30d0aa3af413d2aa5ae4f23c66d78980072d1e07a5b0d776e9606a2f0b9 hi
...
$ docker model ps
MODEL NAME                           BACKEND    MODE        LAST USED
index.docker.io/ai/smollm2-2:latest  llama.cpp  completion  2 seconds ago

Now:

$ docker model run sha256:354bf30d0aa3af413d2aa5ae4f23c66d78980072d1e07a5b0d776e9606a2f0b9 hi
...
$ docker model ps
MODEL NAME                                                               BACKEND    MODE        LAST USED
sha256:354bf30d0aa3af413d2aa5ae4f23c66d78980072d1e07a5b0d776e9606a2f0b9  llama.cpp  completion  2 seconds ago

Moreover, with the second commit, the previous ps output will look like this:

$ docker model ps
MODEL NAME    BACKEND    MODE        LAST USED
354bf30d0aa3  llama.cpp  completion  8 seconds ago