test(03-01): add failing tests for DailyPlanDao cross-room query and completion count

- 7 failing tests for watchAllTasksWithRoomName and watchCompletionsToday
- DAO stub with UnimplementedError methods registered in AppDatabase
- TaskWithRoom and DailyPlanState model classes defined

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/features/home/domain/daily_plan_models.dart

@@ -0,0 +1,31 @@
+import 'package:household_keeper/core/database/database.dart';
+
+/// A task paired with its room for daily plan display.
+class TaskWithRoom {
+  final Task task;
+  final String roomName;
+  final int roomId;
+
+  const TaskWithRoom({
+    required this.task,
+    required this.roomName,
+    required this.roomId,
+  });
+}
+
+/// Daily plan data categorized into sections with progress tracking.
+class DailyPlanState {
+  final List<TaskWithRoom> overdueTasks;
+  final List<TaskWithRoom> todayTasks;
+  final List<TaskWithRoom> tomorrowTasks;
+  final int completedTodayCount;
+  final int totalTodayCount;
+
+  const DailyPlanState({
+    required this.overdueTasks,
+    required this.todayTasks,
+    required this.tomorrowTasks,
+    required this.completedTodayCount,
+    required this.totalTodayCount,
+  });
+}