added habit_streaks to habits table

supabase/migrations/20260524150000_habits_streak.sql

@@ -0,0 +1,20 @@
+alter table public.habits
+  add column if not exists streak int not null default 0,
+  add column if not exists last_completed_on date;
+
+alter table public.habits
+  drop constraint if exists habits_streak_check;
+
+alter table public.habits
+  add constraint habits_streak_check
+    check (streak >= 0);
+
+update public.habits h
+set last_completed_on = latest.completed_on
+from (
+  select habit_id, max(completed_on) as completed_on
+  from public.habit_logs
+  group by habit_id
+) as latest
+where h.id = latest.habit_id
+  and h.last_completed_on is null;