Make `hsm push` error if source script file's name is not compatible with hackmud script name

We had a user not realising the didn't need the `.src` in their script source (they were switching from using `hsm minify` to `hsm push`), and HSM didn't bat an eye and gave a confusing error message.

We should instead give a useful error message and explain the name they used isn't compatible with hackmud