Devlog 7 - Exam Countdown Feature

I added an exam countdown feature to the Study Planner.

Each subject already had an exam date, but the date by itself was not very useful. To make the information easier to understand,

I added a countdown that shows how many days are left until the exam.

When a subject is created, the planner now calculates the difference between the current date and the selected exam date.
The result is displayed directly below the exam date.

I also handled a few different situations. If no exam date is selected, the planner shows a message to let the user know.
If the exam date is today, a special message is displayed. If the date has already passed, the planner will show that as well.

After adding the countdown feature, I tested it with different dates to make sure the calculation worked correctly.