Should -d flag just be a -i string input

As is becoming clear when I'm writing out the manual, `-d` is really just a different way to randomly seed a seed, like -i dice, -i cards, etc. Consistency would suggest it should be -i seedphrase.

Start by tracing the CLI argument parsing and the existing handling of `-d` and `-i`. Compare the documented manual behavior with the implementation and current tests, then confirm whether `-d` should become the `-i seedphrase` input described in the issue. Done means the interface is consistent and its behavior is covered by tests or documentation.

Written by the indexing model from the issue text.