Added stub screens

Used as a placeholder,
whilst other screens are currently worked on.

NOTE: there is no finished specification for
Products and Shopping List Items

lib/screens/room/categories.dart

@@ -0,0 +1,19 @@
+import 'package:flutter/material.dart';
+import 'package:outbag_app/backend/room.dart';
+
+class RoomCategoriesPage extends StatefulWidget {
+  final RoomInfo? info;
+  final Room? room;
+
+  const RoomCategoriesPage(this.room, this.info, {super.key});
+
+  @override
+  State<StatefulWidget> createState() => _RoomCategoriesPageState();
+}
+
+class _RoomCategoriesPageState extends State<RoomCategoriesPage> {
+  @override
+  Widget build(BuildContext context) {
+    return const Text('Categories');
+  }
+}

lib/screens/room/products.dart

@@ -0,0 +1,19 @@
+import 'package:flutter/material.dart';
+import 'package:outbag_app/backend/room.dart';
+
+class RoomProductsPage extends StatefulWidget {
+  final RoomInfo? info;
+  final Room? room;
+
+  const RoomProductsPage(this.room, this.info, {super.key});
+
+  @override
+  State<StatefulWidget> createState() => _RoomProductsPageState();
+}
+
+class _RoomProductsPageState extends State<RoomProductsPage> {
+  @override
+  Widget build(BuildContext context) {
+    return const Text('Products');
+  }
+}

lib/screens/room/shopping_list.dart

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+import 'package:flutter/material.dart';
+import 'package:outbag_app/backend/room.dart';
+
+class ShoppingListPage extends StatefulWidget {
+  final RoomInfo? info;
+  final Room? room;
+
+  const ShoppingListPage(this.room, this.info, {super.key});
+
+  @override
+  State<StatefulWidget> createState() => _ShoppingListPageState();
+}
+
+class _ShoppingListPageState extends State<ShoppingListPage> {
+  List<ShoppingListItem> list = [];
+
+  void loadData() async {
+    //bool foundData = false;
+
+    // TODO: 1. load data from disk (if available)
+    // NOTE: errors do not matter,
+    // hopefully the network request will succeed
+    try {
+      //List<ShoppingListItem> list = await ShoppingListItem.getAllFromDisk();
+      //setState(() {
+      //  this.list = list;
+      //})
+
+      //foundData = true;
+    } catch (_) {}
+
+    // TODO: 2. load data from web
+
+    // NOTE: might want to close room
+    // or show snackbar if no data is available
+  }
+
+  @override
+  void initState() {
+    super.initState();
+
+    loadData();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ListView.builder(
+      itemBuilder: (ctx, index) {
+        final item = list[index];
+
+        return ListTile();
+      },
+      itemCount: list.length,
+    );
+  }
+}