add day-detail view to monthly history calendar

날짜 셀 클릭 시 그 날 예정된 습관별 완료/실패/미완료 상태를 htmx로 불러와 보여준다.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_log_service.py

@@ -407,6 +407,53 @@ def test_get_monthly_summary_does_not_count_failed_as_checked(db_session, test_u
     assert by_date[date(2026, 3, 5)].checked_count == 0
 
 
+# ---- get_day_detail ----
+
+
+def test_get_day_detail_marks_checked_and_failed(db_session, test_user):
+    checked_habit = _make_habit(db_session, test_user.id, name="체크됨", created_at=datetime(2026, 3, 1))
+    failed_habit = _make_habit(db_session, test_user.id, name="실패함", created_at=datetime(2026, 3, 1))
+    _check(db_session, checked_habit.id, date(2026, 3, 5))
+    _fail(db_session, failed_habit.id, date(2026, 3, 5))
+
+    items = log_service.get_day_detail(db_session, test_user.id, date(2026, 3, 5))
+    by_name = {i.name: i for i in items}
+    assert by_name["체크됨"].status == "checked"
+    assert by_name["실패함"].status == "failed"
+
+
+def test_get_day_detail_marks_past_unlogged_as_missed(db_session, test_user):
+    habit = _make_habit(db_session, test_user.id, created_at=datetime(2026, 3, 1))
+
+    items = log_service.get_day_detail(db_session, test_user.id, date(2026, 3, 5))
+    assert items[0].status == "missed"
+
+
+def test_get_day_detail_marks_future_unlogged_as_pending(db_session, test_user):
+    habit = _make_habit(db_session, test_user.id)
+    future = date.today() + timedelta(days=1)
+
+    items = log_service.get_day_detail(db_session, test_user.id, future)
+    assert items[0].status == "pending"
+
+
+def test_get_day_detail_excludes_days_before_habit_created(db_session, test_user):
+    _make_habit(db_session, test_user.id, created_at=datetime(2026, 3, 10))
+
+    items = log_service.get_day_detail(db_session, test_user.id, date(2026, 3, 5))
+    assert items == []
+
+
+def test_get_day_detail_excludes_unscheduled_weekdays(db_session, test_user):
+    monday_only_mask = 0b0000001  # bit0 = 월요일
+    _make_habit(db_session, test_user.id, created_at=datetime(2026, 3, 1), weekdays_mask=monday_only_mask)
+
+    tuesday = date(2026, 3, 3)
+    assert tuesday.weekday() == 1
+    items = log_service.get_day_detail(db_session, test_user.id, tuesday)
+    assert items == []
+
+
 # ---- summarize_completion_rate: 미래 날짜 제외 회귀 테스트 ----
 # CLAUDE.md에 기록된 실제 버그: 미래 날짜를 포함시키면 완료율이 부당하게 낮게 나온다
 # (실제로 6.2% -> 수정 후 50%가 된 사례).