add abandoned status to distinguish given-up habits from completed ones

Completed and abandoned habits were both lumped under a single terminal
state, making it impossible to tell "finished successfully" apart from
"gave up" when reviewing habit history.

tests/test_habit_service.py

@@ -86,6 +86,30 @@ def test_complete_and_reactivate_habit(db_session, test_user):
     assert reactivated.completed_at is None
 
 
+def test_abandon_and_reactivate_habit(db_session, test_user):
+    habit = _make_habit(db_session, test_user.id)
+
+    abandoned = habit_service.abandon_habit(db_session, habit)
+    assert abandoned.status == HabitStatus.ABANDONED
+    assert abandoned.abandoned_at is not None
+
+    reactivated = habit_service.reactivate_habit(db_session, habit)
+    assert reactivated.status == HabitStatus.ACTIVE
+    assert reactivated.abandoned_at is None
+
+
+def test_list_habits_filters_by_abandoned_status(db_session, test_user):
+    build = _make_habit(db_session, test_user.id, name="빌드")
+    quit_ = _make_habit(db_session, test_user.id, name="퀴트", habit_type=HabitType.QUIT)
+    habit_service.abandon_habit(db_session, quit_)
+
+    active = habit_service.list_habits(db_session, test_user.id, status=HabitStatus.ACTIVE)
+    assert [h.id for h in active] == [build.id]
+
+    abandoned = habit_service.list_habits(db_session, test_user.id, status=HabitStatus.ABANDONED)
+    assert [h.id for h in abandoned] == [quit_.id]
+
+
 def test_reorder_habits_applies_given_order(db_session, test_user):
     a = _make_habit(db_session, test_user.id, name="A")
     b = _make_habit(db_session, test_user.id, name="B")