Rings

New Stats tab: check-ins, longest streak, perfect days, a 12-week heatmap and each habit's last 4 weeks.

Habits now have their own icon and colour; your existing habits keep their days and streaks, get a ✨ icon and keep their colour. Bigger tap targets for the day dots.

First version: a dark habit tracker built around animated rings, with streaks, weekly targets and a 7-day strip