Add “most neglected” sorting based on habit frequency

[Ploppz]

Hi, I just started using this wonderful app and I'm exploring whether it fits my use case.

I would like a way to sort habits by "most neglected" - essentially, which habit is most overdue relative to its configured frequency. This would let the list function as a gentle priority view: if I'm unsure what to do today, I can start with the habit that has drifted furthest from its intended cadence.

A simple version could sort by the number of days since the habit was last completed. (This is very similar to the "Status" sort I think? but "Status" sort only seems to care about today, not number of no-days)

A more useful version might normalize this by the habit's target frequency. For example, a 3-day gap is very significant for a daily habit, but not very significant for a monthly habit. So the sort key could be something like:

days_since_last_completion / expected_interval_days

This would make low-frequency habits and high-frequency habits comparable.

My use case is not strict streak enforcement, but “best effort” maintenance of recurring practices. I don't mind breaks; I just want to see which practice most needs renewed attention.

I'd be interested in making a PR if this sounds aligned with the project, or discussing what the feature should look like.

[Ploppz]

I just found that this is similar to #921 , but proposing a different solution here to perhaps the same desire.