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/l10n/app_de.arb

@@ -68,5 +68,25 @@
     "placeholders": {
       "count": { "type": "int" }
     }
-  }
+  },
+  "dailyPlanProgress": "{completed} von {total} erledigt",
+  "@dailyPlanProgress": {
+    "placeholders": {
+      "completed": { "type": "int" },
+      "total": { "type": "int" }
+    }
+  },
+  "dailyPlanSectionOverdue": "\u00dcberf\u00e4llig",
+  "dailyPlanSectionToday": "Heute",
+  "dailyPlanSectionUpcoming": "Demn\u00e4chst",
+  "dailyPlanUpcomingCount": "Demn\u00e4chst ({count})",
+  "@dailyPlanUpcomingCount": {
+    "placeholders": {
+      "count": { "type": "int" }
+    }
+  },
+  "dailyPlanAllClearTitle": "Alles erledigt! \ud83c\udf1f",
+  "dailyPlanAllClearMessage": "Keine Aufgaben f\u00fcr heute. Genie\u00dfe den Moment!",
+  "dailyPlanNoOverdue": "Keine \u00fcberf\u00e4lligen Aufgaben",
+  "dailyPlanNoTasks": "Noch keine Aufgaben angelegt"
 }

lib/l10n/app_localizations.dart

@@ -417,6 +417,60 @@ abstract class AppLocalizations {
   /// In de, this message translates to:
   /// **'{count} ausgewählt'**
   String templatePickerSelected(int count);
+
+  /// No description provided for @dailyPlanProgress.
+  ///
+  /// In de, this message translates to:
+  /// **'{completed} von {total} erledigt'**
+  String dailyPlanProgress(int completed, int total);
+
+  /// No description provided for @dailyPlanSectionOverdue.
+  ///
+  /// In de, this message translates to:
+  /// **'Überfällig'**
+  String get dailyPlanSectionOverdue;
+
+  /// No description provided for @dailyPlanSectionToday.
+  ///
+  /// In de, this message translates to:
+  /// **'Heute'**
+  String get dailyPlanSectionToday;
+
+  /// No description provided for @dailyPlanSectionUpcoming.
+  ///
+  /// In de, this message translates to:
+  /// **'Demnächst'**
+  String get dailyPlanSectionUpcoming;
+
+  /// No description provided for @dailyPlanUpcomingCount.
+  ///
+  /// In de, this message translates to:
+  /// **'Demnächst ({count})'**
+  String dailyPlanUpcomingCount(int count);
+
+  /// No description provided for @dailyPlanAllClearTitle.
+  ///
+  /// In de, this message translates to:
+  /// **'Alles erledigt! 🌟'**
+  String get dailyPlanAllClearTitle;
+
+  /// No description provided for @dailyPlanAllClearMessage.
+  ///
+  /// In de, this message translates to:
+  /// **'Keine Aufgaben für heute. Genieße den Moment!'**
+  String get dailyPlanAllClearMessage;
+
+  /// No description provided for @dailyPlanNoOverdue.
+  ///
+  /// In de, this message translates to:
+  /// **'Keine überfälligen Aufgaben'**
+  String get dailyPlanNoOverdue;
+
+  /// No description provided for @dailyPlanNoTasks.
+  ///
+  /// In de, this message translates to:
+  /// **'Noch keine Aufgaben angelegt'**
+  String get dailyPlanNoTasks;
 }
 
 class _AppLocalizationsDelegate

lib/l10n/app_localizations_de.dart

@@ -178,4 +178,36 @@ class AppLocalizationsDe extends AppLocalizations {
   String templatePickerSelected(int count) {
     return '$count ausgewählt';
   }
+
+  @override
+  String dailyPlanProgress(int completed, int total) {
+    return '$completed von $total erledigt';
+  }
+
+  @override
+  String get dailyPlanSectionOverdue => 'Überfällig';
+
+  @override
+  String get dailyPlanSectionToday => 'Heute';
+
+  @override
+  String get dailyPlanSectionUpcoming => 'Demnächst';
+
+  @override
+  String dailyPlanUpcomingCount(int count) {
+    return 'Demnächst ($count)';
+  }
+
+  @override
+  String get dailyPlanAllClearTitle => 'Alles erledigt! 🌟';
+
+  @override
+  String get dailyPlanAllClearMessage =>
+      'Keine Aufgaben für heute. Genieße den Moment!';
+
+  @override
+  String get dailyPlanNoOverdue => 'Keine überfälligen Aufgaben';
+
+  @override
+  String get dailyPlanNoTasks => 'Noch keine Aufgaben angelegt';
 }