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_pages_history.py

@@ -0,0 +1,41 @@
+from datetime import date, datetime
+
+from app.models.habit import ALL_WEEKDAYS_MASK, HabitType
+from app.schemas.habit import HabitCreate
+from app.services import habit_service
+
+
+def _make_habit(db_session, user_id, name="테스트 습관", created_at=None, **overrides):
+    data = HabitCreate(
+        name=name,
+        habit_type=overrides.pop("habit_type", HabitType.BUILD),
+        weekdays_mask=overrides.pop("weekdays_mask", ALL_WEEKDAYS_MASK),
+    )
+    habit = habit_service.create_habit(db_session, user_id, data)
+    if created_at is not None:
+        habit.created_at = created_at
+        db_session.commit()
+        db_session.refresh(habit)
+    return habit
+
+
+def test_history_day_detail_shows_scheduled_habit(auth_client, db_session, test_user):
+    _make_habit(db_session, test_user.id, name="아침 스트레칭", created_at=datetime(2026, 3, 1))
+
+    response = auth_client.get("/history/day/2026-03-05")
+    assert response.status_code == 200
+    assert "아침 스트레칭" in response.text
+
+
+def test_history_day_detail_excludes_other_users_habits(auth_client, db_session, other_user):
+    _make_habit(db_session, other_user.id, name="남의 습관", created_at=datetime(2026, 3, 1))
+
+    response = auth_client.get("/history/day/2026-03-05")
+    assert response.status_code == 200
+    assert "남의 습관" not in response.text
+
+
+def test_history_day_detail_requires_login(client):
+    response = client.get("/history/day/2026-03-05", follow_redirects=False)
+    assert response.status_code == 303
+    assert response.headers["location"] == "/login"