Add household sharing feature

✨ Features:
- Create household with 6-character shareable code
- Join existing household with code
- View household members and owner
- Leave household functionality
- Automatic inventory filtering by household
- Persistent household settings across app updates

🔧 Technical changes:
- Added Household model with Hive adapter (typeId: 4)
- Updated AppSettings with userName and currentHouseholdId fields
- Modified InventoryRepository to filter items by household
- Updated Add Item screen to set householdId on new items
- Added HouseholdScreen with full CRUD operations
- Integrated household sharing into Settings navigation

🎯 Behavior:
- Users not in a household see only their personal items
- Users in a household see shared household items
- New items automatically tagged with current household

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/features/settings/models/app_settings.dart

@@ -19,11 +19,19 @@ class AppSettings extends HiveObject {
   @HiveField(4)
   String sortBy; // 'expiration', 'name', 'location'
 
+  @HiveField(5)
+  String? userName; // User's name for household sharing
+
+  @HiveField(6)
+  String? currentHouseholdId; // ID of the household they're in
+
   AppSettings({
     this.discordWebhookUrl,
     this.expirationAlertsEnabled = true,
     this.discordNotificationsEnabled = false,
     this.defaultView = 'grid',
     this.sortBy = 'expiration',
+    this.userName,
+    this.currentHouseholdId,
   });
 }

lib/features/settings/models/app_settings.g.dart

@@ -22,13 +22,15 @@ class AppSettingsAdapter extends TypeAdapter<AppSettings> {
       discordNotificationsEnabled: fields[2] as bool,
       defaultView: fields[3] as String,
       sortBy: fields[4] as String,
+      userName: fields[5] as String?,
+      currentHouseholdId: fields[6] as String?,
     );
   }
 
   @override
   void write(BinaryWriter writer, AppSettings obj) {
     writer
-      ..writeByte(5)
+      ..writeByte(7)
       ..writeByte(0)
       ..write(obj.discordWebhookUrl)
       ..writeByte(1)
@@ -38,7 +40,11 @@ class AppSettingsAdapter extends TypeAdapter<AppSettings> {
       ..writeByte(3)
       ..write(obj.defaultView)
       ..writeByte(4)
-      ..write(obj.sortBy);
+      ..write(obj.sortBy)
+      ..writeByte(5)
+      ..write(obj.userName)
+      ..writeByte(6)
+      ..write(obj.currentHouseholdId);
   }
 
   @override

lib/features/settings/models/household.dart

@@ -0,0 +1,45 @@
+import 'package:hive/hive.dart';
+
+part 'household.g.dart';
+
+@HiveType(typeId: 4)
+class Household extends HiveObject {
+  @HiveField(0)
+  late String id; // Unique household code
+
+  @HiveField(1)
+  late String name;
+
+  @HiveField(2)
+  late String ownerName; // Person who created the household
+
+  @HiveField(3)
+  late DateTime createdAt;
+
+  @HiveField(4)
+  List<String> members; // List of member names
+
+  Household({
+    required this.id,
+    required this.name,
+    required this.ownerName,
+    DateTime? createdAt,
+    List<String>? members,
+  })  : createdAt = createdAt ?? DateTime.now(),
+        members = members ?? [];
+
+  /// Generate a random household code
+  static String generateCode() {
+    const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
+    final random = DateTime.now().millisecondsSinceEpoch;
+    var code = '';
+    var seed = random;
+
+    for (var i = 0; i < 6; i++) {
+      seed = (seed * 1103515245 + 12345) & 0x7fffffff;
+      code += chars[seed % chars.length];
+    }
+
+    return code;
+  }
+}

lib/features/settings/models/household.g.dart

@@ -0,0 +1,53 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'household.dart';
+
+// **************************************************************************
+// TypeAdapterGenerator
+// **************************************************************************
+
+class HouseholdAdapter extends TypeAdapter<Household> {
+  @override
+  final int typeId = 4;
+
+  @override
+  Household read(BinaryReader reader) {
+    final numOfFields = reader.readByte();
+    final fields = <int, dynamic>{
+      for (int i = 0; i < numOfFields; i++) reader.readByte(): reader.read(),
+    };
+    return Household(
+      id: fields[0] as String,
+      name: fields[1] as String,
+      ownerName: fields[2] as String,
+      createdAt: fields[3] as DateTime?,
+      members: (fields[4] as List?)?.cast<String>(),
+    );
+  }
+
+  @override
+  void write(BinaryWriter writer, Household obj) {
+    writer
+      ..writeByte(5)
+      ..writeByte(0)
+      ..write(obj.id)
+      ..writeByte(1)
+      ..write(obj.name)
+      ..writeByte(2)
+      ..write(obj.ownerName)
+      ..writeByte(3)
+      ..write(obj.createdAt)
+      ..writeByte(4)
+      ..write(obj.members);
+  }
+
+  @override
+  int get hashCode => typeId.hashCode;
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is HouseholdAdapter &&
+          runtimeType == other.runtimeType &&
+          typeId == other.typeId;
+}