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/moments/domain/README.md

@@ -0,0 +1,4 @@
+# Moments Domain
+
+Relationship capture and timeline models live here. Keep this folder focused on
+recorded events and notes about interactions.

lib/features/moments/domain/moment_models.dart

@@ -0,0 +1,63 @@
+// ignore_for_file: sort_constructors_first
+
+import 'package:flutter/foundation.dart';
+
+/// Timeline event stored for a specific relationship.
+@immutable
+class RelationshipMoment {
+  const RelationshipMoment({
+    required this.id,
+    required this.personId,
+    required this.title,
+    required this.summary,
+    required this.at,
+    required this.type,
+  });
+
+  final String id;
+  final String personId;
+  final String title;
+  final String summary;
+  final DateTime at;
+  final String type;
+
+  RelationshipMoment copyWith({
+    String? id,
+    String? personId,
+    String? title,
+    String? summary,
+    DateTime? at,
+    String? type,
+  }) {
+    return RelationshipMoment(
+      id: id ?? this.id,
+      personId: personId ?? this.personId,
+      title: title ?? this.title,
+      summary: summary ?? this.summary,
+      at: at ?? this.at,
+      type: type ?? this.type,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return <String, dynamic>{
+      'id': id,
+      'personId': personId,
+      'title': title,
+      'summary': summary,
+      'at': at.toUtc().toIso8601String(),
+      'type': type,
+    };
+  }
+
+  factory RelationshipMoment.fromJson(Map<String, dynamic> json) {
+    return RelationshipMoment(
+      id: json['id'] as String,
+      personId: json['personId'] as String,
+      title: json['title'] as String,
+      summary: json['summary'] as String,
+      at: DateTime.parse(json['at'] as String).toLocal(),
+      type: json['type'] as String,
+    );
+  }
+}