- Add `ShoppingListMemberEntity` table with foreign key cascade to shopping lists
- Add `backgroundResName`, `region`, `sortType`, `displayOrder`, `visibleCategories` fields to `ShoppingListEntity`
- Increment database version to 6
- Implement member CRUD operations in DAO and repository layers
- Add `observeMembers`, `addMember`, `updateMember`, `removeMember` methods across data/domain layers
- Update