The signature screen showed only the text a personal message decodes
to, with bidirectional and zero-width characters acting on it, so a
site could make the message read differently from the bytes that are
signed, and a message that was not hex was decoded into NUL
characters. The screen now shows the hex as "Raw data" alongside the
decoded text, and each control or format character in the text as a
U+XXXX mark. Signing takes the bytes from the hex, so a message that
is not hex cannot be signed: it is shown as plain text, with the error
line saying so and "Sign" disabled.
Model: opus-5-5
