feat: add local-first private AI digest workflow

Migrate app code into canonical feature slices, add phone-only AI digest scheduling and review, wire local notification/background task support, and cover the flow with tests.

lib/features/reminders/domain/reminder_models.dart

@@ -0,0 +1,71 @@
+// ignore_for_file: sort_constructors_first
+
+import 'package:flutter/foundation.dart';
+
+/// Reminder cadence supported by the local scheduling layer.
+enum ReminderCadence { daily, weekly, monthly }
+
+/// Reminder rule stored locally and optionally synced later.
+@immutable
+class ReminderRule {
+  const ReminderRule({
+    required this.id,
+    required this.title,
+    required this.cadence,
+    required this.nextAt,
+    this.personId,
+    this.enabled = true,
+  });
+
+  final String id;
+  final String? personId;
+  final String title;
+  final ReminderCadence cadence;
+  final DateTime nextAt;
+  final bool enabled;
+
+  ReminderRule copyWith({
+    String? id,
+    String? personId,
+    String? title,
+    ReminderCadence? cadence,
+    DateTime? nextAt,
+    bool? enabled,
+  }) {
+    return ReminderRule(
+      id: id ?? this.id,
+      personId: personId ?? this.personId,
+      title: title ?? this.title,
+      cadence: cadence ?? this.cadence,
+      nextAt: nextAt ?? this.nextAt,
+      enabled: enabled ?? this.enabled,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return <String, dynamic>{
+      'id': id,
+      'personId': personId,
+      'title': title,
+      'cadence': cadence.name,
+      'nextAt': nextAt.toUtc().toIso8601String(),
+      'enabled': enabled,
+    };
+  }
+
+  factory ReminderRule.fromJson(Map<String, dynamic> json) {
+    final String cadenceName =
+        json['cadence'] as String? ?? ReminderCadence.weekly.name;
+    return ReminderRule(
+      id: json['id'] as String,
+      personId: json['personId'] as String?,
+      title: json['title'] as String,
+      cadence: ReminderCadence.values.firstWhere(
+        (ReminderCadence cadence) => cadence.name == cadenceName,
+        orElse: () => ReminderCadence.weekly,
+      ),
+      nextAt: DateTime.parse(json['nextAt'] as String).toLocal(),
+      enabled: json['enabled'] as bool? ?? true,
+    );
+  }
+}