feat(03-01): add daily plan provider with date categorization and localization keys

- dailyPlanProvider: manual StreamProvider.autoDispose with overdue/today/tomorrow partitioning
- Stable progress denominator: remaining overdue + remaining today + completedTodayCount
- 10 new German localization keys for daily plan sections, progress, empty states
- dart analyze clean, full test suite (66/66) passes

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

lib/features/home/presentation/daily_plan_providers.dart

@@ -0,0 +1,56 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'package:household_keeper/core/providers/database_provider.dart';
+import 'package:household_keeper/features/home/domain/daily_plan_models.dart';
+
+/// Reactive daily plan data: tasks categorized into overdue/today/tomorrow
+/// with progress tracking.
+///
+/// Defined manually (not @riverpod) because riverpod_generator has trouble
+/// with drift's generated [Task] type. Same pattern as [tasksInRoomProvider].
+final dailyPlanProvider =
+    StreamProvider.autoDispose<DailyPlanState>((ref) {
+  final db = ref.watch(appDatabaseProvider);
+  final taskStream = db.dailyPlanDao.watchAllTasksWithRoomName();
+
+  return taskStream.asyncMap((allTasks) async {
+    // Get today's completion count (latest value from stream)
+    final completedToday =
+        await db.dailyPlanDao.watchCompletionsToday().first;
+
+    final now = DateTime.now();
+    final today = DateTime(now.year, now.month, now.day);
+    final tomorrow = today.add(const Duration(days: 1));
+    final dayAfterTomorrow = tomorrow.add(const Duration(days: 1));
+
+    final overdue = <TaskWithRoom>[];
+    final todayList = <TaskWithRoom>[];
+    final tomorrowList = <TaskWithRoom>[];
+
+    for (final tw in allTasks) {
+      final dueDate = DateTime(
+        tw.task.nextDueDate.year,
+        tw.task.nextDueDate.month,
+        tw.task.nextDueDate.day,
+      );
+      if (dueDate.isBefore(today)) {
+        overdue.add(tw);
+      } else if (dueDate.isBefore(tomorrow)) {
+        todayList.add(tw);
+      } else if (dueDate.isBefore(dayAfterTomorrow)) {
+        tomorrowList.add(tw);
+      }
+    }
+
+    // totalTodayCount includes completedTodayCount so the denominator
+    // stays stable as tasks are completed (their nextDueDate moves to
+    // the future, shrinking overdue+today, but completedToday grows).
+    return DailyPlanState(
+      overdueTasks: overdue,
+      todayTasks: todayList,
+      tomorrowTasks: tomorrowList,
+      completedTodayCount: completedToday,
+      totalTodayCount: overdue.length + todayList.length + completedToday,
+    );
+  });
+});