Guard against a private.key having no line breaks

Some windows bash programs copy the private key with line breaks. This screws up the jwt token generation. We should use the fixed line length to add in the line breaks where needed.

Start by tracing the JavaScript JWT token generation path and how private.key is read. Reproduce the case where the key has no line breaks, then verify that fixed-length line breaks are restored and JWT generation succeeds.

Written by the indexing model from the issue text.