feat: Saving the exercise day with a title and notes

Before IronFlow I used the notes-app on my phone to log my training. There, each training date is logged with a name (Chest + triceps, back + biceps, legs, etc.). This makes it easy to go back to my last chest day and see what exercises I did and how much I lifted. In IronFlow I now have to remember what date my last chest day was on, which doesn't work well for me, since I have poor memory and no set weekday for each muscle group. I want to be able to save each day of exercise with a title and maybe some notes for myself, and for these days to be easy to access. I am unsure about how this would be best implemented in the app currently.