Create better command handling

Change the UI to look more like how Linux uses text commands.
Instead of prompting a command and then an input, the program could do it more like how Git does:
-e Sphinx of Black Quartz, Judge My Vow!
and
-d ĀA̰Á A̤ÄẢA̧Ạ A̮ÅA̽ A̓ÄǍA̯Ã ÅÀÁȂ ĀA̰Á ĂAȺA̦ A̱ÅA̋

- Look at [Git's user manual](https://git-scm.com/docs/user-manual) for inspiration.
- Update the command handling.

Read Git's user manual for command-line interaction inspiration, then inspect the project's existing command prompt and input handling. Done means the UI accepts the requested command-style options, including the shown encryption and decryption examples, instead of prompting separately for a command and input.

Written by the indexing model from the issue text.