Verify input when outside boundaries

[PossibleLlama]

Is your feature request related to a problem? Please describe.
Ability to specify conditions, which if the input doesn't match, it asks for stdin, or rejects.

Describe the solution you'd like
Within the config, a regex is supplied for each field (such as title), which is compared against when creating or editing. If the input doesn't match that, it seeks from stdin.

A command line arg (--verify-reject ?) can be used to ignore stdin and cause an exit code instead.

Use case

• When using a card system setting a regex that the title must match.
• Needing the when date to be within x days of now.

[PossibleLlama]

This will very much be a nice to have, but isn't a high priority especially now with a UI where we can perform this validation client side.
It would be useful to get the validation of fields other than when, as that will be the more difficult one to implement in an intuitive way in the config.

Potentially this whole issue will make more sense once the CLI has an interactive section and is asking for inputs.