* convert_lora : use the lora dir for the model card path

Multiple finetune versions are now joined together,
and the removal of the basename annotation on trailing versions
is more robust.

The default filename was previously hardcoded.

* convert_hf : Model.fname_out can no longer be None

Some models use acronyms in lowercase,
which can't be title-cased like other words,
so it's best to simply use the same case
as in the original model name.

Note that the size label still has an uppercased suffix
to make it distinguishable from the context size of a finetune.