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/inventory/repositories/inventory_repository_impl.dart

@@ -1,5 +1,6 @@
 import 'package:hive/hive.dart';
 import '../../../data/local/hive_database.dart';
+import '../../settings/models/app_settings.dart';
 import '../models/food_item.dart';
 import 'inventory_repository.dart';
 
@@ -7,10 +8,32 @@ import 'inventory_repository.dart';
 class InventoryRepositoryImpl implements InventoryRepository {
   Future<Box<FoodItem>> get _box async => await HiveDatabase.getFoodBox();
 
+  /// Get the current household ID from settings
+  Future<String?> get _currentHouseholdId async {
+    final settings = await HiveDatabase.getSettings();
+    return settings.currentHouseholdId;
+  }
+
+  /// Filter items by current household
+  /// If user is in a household, only show items from that household
+  /// If user is not in a household, only show items without a household
+  List<FoodItem> _filterByHousehold(Iterable<FoodItem> items, String? householdId) {
+    return items.where((item) {
+      if (householdId == null) {
+        // User not in household - show items without household
+        return item.householdId == null;
+      } else {
+        // User in household - show items from that household
+        return item.householdId == householdId;
+      }
+    }).toList();
+  }
+
   @override
   Future<List<FoodItem>> getAllItems() async {
     final box = await _box;
-    return box.values.toList();
+    final householdId = await _currentHouseholdId;
+    return _filterByHousehold(box.values, householdId);
   }
 
   @override
@@ -41,7 +64,9 @@ class InventoryRepositoryImpl implements InventoryRepository {
   @override
   Future<List<FoodItem>> getItemsByLocation(Location location) async {
     final box = await _box;
-    return box.values
+    final householdId = await _currentHouseholdId;
+    final filteredItems = _filterByHousehold(box.values, householdId);
+    return filteredItems
         .where((item) => item.location == location)
         .toList();
   }
@@ -49,8 +74,10 @@ class InventoryRepositoryImpl implements InventoryRepository {
   @override
   Future<List<FoodItem>> getItemsExpiringWithinDays(int days) async {
     final box = await _box;
+    final householdId = await _currentHouseholdId;
+    final filteredItems = _filterByHousehold(box.values, householdId);
     final targetDate = DateTime.now().add(Duration(days: days));
-    return box.values
+    return filteredItems
         .where((item) =>
             item.expirationDate.isBefore(targetDate) &&
             item.expirationDate.isAfter(DateTime.now()))
@@ -61,7 +88,9 @@ class InventoryRepositoryImpl implements InventoryRepository {
   @override
   Future<List<FoodItem>> getExpiredItems() async {
     final box = await _box;
-    return box.values
+    final householdId = await _currentHouseholdId;
+    final filteredItems = _filterByHousehold(box.values, householdId);
+    return filteredItems
         .where((item) => item.expirationDate.isBefore(DateTime.now()))
         .toList()
       ..sort((a, b) => a.expirationDate.compareTo(b.expirationDate));
@@ -70,8 +99,10 @@ class InventoryRepositoryImpl implements InventoryRepository {
   @override
   Future<List<FoodItem>> searchItemsByName(String query) async {
     final box = await _box;
+    final householdId = await _currentHouseholdId;
+    final filteredItems = _filterByHousehold(box.values, householdId);
     final lowerQuery = query.toLowerCase();
-    return box.values
+    return filteredItems
         .where((item) => item.name.toLowerCase().contains(lowerQuery))
         .toList();
   }
@@ -79,32 +110,40 @@ class InventoryRepositoryImpl implements InventoryRepository {
   @override
   Future<int> getItemCount() async {
     final box = await _box;
-    return box.length;
+    final householdId = await _currentHouseholdId;
+    final filteredItems = _filterByHousehold(box.values, householdId);
+    return filteredItems.length;
   }
 
   @override
   Stream<List<FoodItem>> watchAllItems() async* {
     final box = await _box;
-    yield box.values.toList();
+    final householdId = await _currentHouseholdId;
+    yield _filterByHousehold(box.values, householdId);
 
     await for (final _ in box.watch()) {
-      yield box.values.toList();
+      final currentHouseholdId = await _currentHouseholdId;
+      yield _filterByHousehold(box.values, currentHouseholdId);
     }
   }
 
   @override
   Stream<List<FoodItem>> watchExpiringItems(int days) async* {
     final box = await _box;
+    final householdId = await _currentHouseholdId;
     final targetDate = DateTime.now().add(Duration(days: days));
 
-    yield box.values
+    final filteredItems = _filterByHousehold(box.values, householdId);
+    yield filteredItems
         .where((item) =>
             item.expirationDate.isBefore(targetDate) &&
             item.expirationDate.isAfter(DateTime.now()))
         .toList();
 
     await for (final _ in box.watch()) {
-      yield box.values
+      final currentHouseholdId = await _currentHouseholdId;
+      final currentFilteredItems = _filterByHousehold(box.values, currentHouseholdId);
+      yield currentFilteredItems
           .where((item) =>
               item.expirationDate.isBefore(targetDate) &&
               item.expirationDate.isAfter(DateTime.now()))

lib/features/inventory/screens/add_item_screen.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:intl/intl.dart';
 import '../../../core/constants/colors.dart';
+import '../../../data/local/hive_database.dart';
 import '../models/food_item.dart';
 import '../controllers/inventory_controller.dart';
 import '../services/barcode_service.dart';
@@ -118,6 +119,9 @@ class _AddItemScreenState extends ConsumerState<AddItemScreen> {
 
   Future<void> _saveItem() async {
     if (_formKey.currentState!.validate()) {
+      // Get current household ID from settings
+      final settings = await HiveDatabase.getSettings();
+
       final item = FoodItem()
         ..name = _nameController.text.trim()
         ..barcode = _barcode
@@ -132,6 +136,7 @@ class _AddItemScreenState extends ConsumerState<AddItemScreen> {
         ..notes = _notesController.text.trim().isEmpty
             ? null
             : _notesController.text.trim()
+        ..householdId = settings.currentHouseholdId
         ..lastModified = DateTime.now();
 
       try {