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/ideas/domain/idea_models.dart

@@ -0,0 +1,76 @@
+// ignore_for_file: sort_constructors_first
+
+import 'package:flutter/foundation.dart';
+
+/// Higher-level bucket for plan and gift suggestions.
+enum IdeaType { gift, event }
+
+/// Saved idea for a person or for the broader relationship backlog.
+@immutable
+class RelationshipIdea {
+  const RelationshipIdea({
+    required this.id,
+    required this.type,
+    required this.title,
+    required this.details,
+    required this.createdAt,
+    this.personId,
+    this.isArchived = false,
+  });
+
+  final String id;
+  final String? personId;
+  final IdeaType type;
+  final String title;
+  final String details;
+  final DateTime createdAt;
+  final bool isArchived;
+
+  RelationshipIdea copyWith({
+    String? id,
+    String? personId,
+    IdeaType? type,
+    String? title,
+    String? details,
+    DateTime? createdAt,
+    bool? isArchived,
+  }) {
+    return RelationshipIdea(
+      id: id ?? this.id,
+      personId: personId ?? this.personId,
+      type: type ?? this.type,
+      title: title ?? this.title,
+      details: details ?? this.details,
+      createdAt: createdAt ?? this.createdAt,
+      isArchived: isArchived ?? this.isArchived,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return <String, dynamic>{
+      'id': id,
+      'personId': personId,
+      'type': type.name,
+      'title': title,
+      'details': details,
+      'createdAt': createdAt.toUtc().toIso8601String(),
+      'isArchived': isArchived,
+    };
+  }
+
+  factory RelationshipIdea.fromJson(Map<String, dynamic> json) {
+    final String typeName = json['type'] as String? ?? IdeaType.gift.name;
+    return RelationshipIdea(
+      id: json['id'] as String,
+      personId: json['personId'] as String?,
+      type: IdeaType.values.firstWhere(
+        (IdeaType type) => type.name == typeName,
+        orElse: () => IdeaType.gift,
+      ),
+      title: json['title'] as String,
+      details: json['details'] as String? ?? '',
+      createdAt: DateTime.parse(json['createdAt'] as String).toLocal(),
+      isArchived: json['isArchived'] as bool? ?? false,
+    );
+  }
+}