Allow subtasks to have deadlines.

[EvelynSays]

Is your feature request related to a problem? Please describe.
I am trying to use the app to plan my classes, and I want each class to contain a sublist of all of my deadlines. I can set a deadline for the overall class, but I can't set a deadline for each subtask. It should look like:

Computer Science

• Assessment 1 (24th March)
• Assessment 2 (1st April)
• Final Exam (6th April)

Describe the solution you'd like
The ability to add deadlines to subtasks. Just that!

Describe alternatives you've considered
Adding each assessment as it's own individual task, which gets very cluttered very quickly.

Additional context
None :)

[Ayagikei]

Hi, thanks for your advice!

Currently, we recommend that you note the deadline directly after the subtask name.

The deadline of the main task is associated with repeated and failed states.

LifeUp's subtasks currently do not involve separate repetitions (but are repeated following the main task) and failure status, and we are not considering introducing separate repetitions, failure statuses and penalties for subtasks for the time being, so whether we want to introduce a deadline may need to be considered.

This may still be discussed and we will collect more user feedback to make a decision.