feat: initial commit - Habo habit tracking app

- Complete MVP with Repository Pattern, SQLite storage
- Provider + ChangeNotifier state management
- Navigation 2.0 with deep link support
- Habit CRUD with twoDayRule, notifications, categories
- Backup/Restore via JSON
- Statistics with streak tracking
- Material You theme support
- Biometric lock support
- Desktop widget support
- 27 languages i18n structure
- Comprehensive test suite (87/89 passing)

lib/statistics/monthly_graph.dart

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+import 'package:flutter/material.dart';
+
+class MonthlyGraph extends StatelessWidget {
+  const MonthlyGraph({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Card(child: Padding(padding: EdgeInsets.all(16), child: Text('Monthly Graph')));
+  }
+}

lib/statistics/overall_statistics_card.dart

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+import 'package:flutter/material.dart';
+
+class OverallStatisticsCard extends StatelessWidget {
+  const OverallStatisticsCard({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Card(child: Padding(padding: EdgeInsets.all(16), child: Text('Overall Statistics')));
+  }
+}

lib/statistics/statistics.dart

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+import 'dart:collection';
+import 'package:habo/constants.dart';
+import 'package:habo/habits/habit.dart';
+import 'package:habo/model/habit_data.dart';
+
+class StatisticsData {
+  String title;
+  int topStreak = 0;
+  int actualStreak = 0;
+  int checks = 0;
+  int fails = 0;
+  int skips = 0;
+  int progress = 0;
+  SplayTreeMap<int, Map<DayType, List<int>>> monthlyTracking;
+
+  StatisticsData({
+    this.title = '',
+    SplayTreeMap<int, Map<DayType, List<int>>>? monthlyTracking,
+  }) : monthlyTracking = monthlyTracking ?? SplayTreeMap<int, Map<DayType, List<int>>>();
+}
+
+class OverallStatisticsData {
+  int totalChecks = 0;
+  int totalFails = 0;
+  int totalSkips = 0;
+  int totalProgress = 0;
+}
+
+class AllStatistics {
+  List<StatisticsData> allStatistics = [];
+  OverallStatisticsData overallStatistics = OverallStatisticsData();
+}
+
+class Statistics {
+  static AllStatistics calculateStatistics(List<Habit> habits) {
+    final result = AllStatistics();
+
+    for (final habit in habits) {
+      final data = StatisticsData(title: habit.habitData.title);
+      final events = habit.habitData.events;
+      bool usingTwoDayRule = false;
+
+      final dates = events.keys.toList();
+      for (int i = 0; i < dates.length; i++) {
+        final date = dates[i];
+        final event = events[date]!;
+        final dayType = event[0] is DayType ? event[0] as DayType : DayType.values[event[0] as int];
+
+        // Check date gap
+        if (i > 0) {
+          final diff = date.difference(dates[i - 1]).inDays;
+          if (diff > 1) {
+            data.actualStreak = 0;
+            usingTwoDayRule = false;
+          }
+        }
+
+        final yearMonth = date.year * 100 + date.month;
+        data.monthlyTracking[yearMonth] ??= {};
+        data.monthlyTracking[yearMonth]![dayType] ??= [];
+        data.monthlyTracking[yearMonth]![dayType]!.add(date.day);
+
+        switch (dayType) {
+          case DayType.check:
+            data.checks++;
+            data.actualStreak++;
+            if (data.actualStreak > data.topStreak) {
+              data.topStreak = data.actualStreak;
+            }
+            usingTwoDayRule = false;
+            break;
+          case DayType.progress:
+            data.progress++;
+            if (habit.habitData.habitType == HabitType.numeric && event.length >= 4) {
+              final progressValue = event[2] as double? ?? 0.0;
+              final target = event[3] as double? ?? habit.habitData.targetValue;
+              if (progressValue >= target) {
+                data.actualStreak++;
+                if (data.actualStreak > data.topStreak) {
+                  data.topStreak = data.actualStreak;
+                }
+              }
+            }
+            usingTwoDayRule = false;
+            break;
+          case DayType.fail:
+            data.fails++;
+            if (habit.habitData.twoDayRule) {
+              if (usingTwoDayRule) {
+                data.actualStreak = 0;
+              } else {
+                usingTwoDayRule = true;
+              }
+            } else {
+              data.actualStreak = 0;
+            }
+            break;
+          case DayType.skip:
+            data.skips++;
+            if (usingTwoDayRule) {
+              data.actualStreak = 0;
+            }
+            break;
+          case DayType.clear:
+            break;
+        }
+      }
+
+      result.allStatistics.add(data);
+    }
+
+    // Calculate overall
+    for (final stat in result.allStatistics) {
+      result.overallStatistics.totalChecks += stat.checks;
+      result.overallStatistics.totalFails += stat.fails;
+      result.overallStatistics.totalSkips += stat.skips;
+      result.overallStatistics.totalProgress += stat.progress;
+    }
+
+    return result;
+  }
+}

lib/statistics/statistics_card.dart

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+import 'package:flutter/material.dart';
+
+class StatisticsCard extends StatelessWidget {
+  const StatisticsCard({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Card(child: Padding(padding: EdgeInsets.all(16), child: Text('Statistics Card')));
+  }
+}

lib/statistics/statistics_screen.dart

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+import 'package:flutter/material.dart';
+
+class StatisticsScreen extends StatelessWidget {
+  const StatisticsScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Statistics')),
+      body: const Center(child: Text('Statistics')),
+    );
+  }
+}