feat: make server own products

lib/views/product_form_view.dart

@@ -12,6 +12,8 @@ import '../models/product.dart';
 import '../utils/money.dart';
 import '../utils/navigation.dart';
 import '../viewmodels/product_list_view_model.dart';
+import '../viewmodels/remote_sync_view_model.dart';
+import 'widgets/managed_on_website_notice.dart';
 
 class ProductFormView extends StatefulWidget {
   final String? productId;
@@ -313,6 +315,9 @@ class _ProductFormViewState extends State<ProductFormView> {
   Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context);
     final title = widget.isEditing ? l10n.editProduct : l10n.addProduct;
+    // A paired tablet gets its products from the website: only the stock and
+    // the picture are changed here
+    final managedOnWebsite = context.watch<RemoteSyncViewModel>().isConfigured;
 
     return Scaffold(
       appBar: AppBar(
@@ -322,7 +327,7 @@ class _ProductFormViewState extends State<ProductFormView> {
           onPressed: _leaveProductForm,
         ),
         actions: [
-          if (widget.isEditing)
+          if (widget.isEditing && !managedOnWebsite)
             IconButton(
               onPressed: _delete,
               icon: const Icon(Icons.delete_outline),
@@ -342,10 +347,15 @@ class _ProductFormViewState extends State<ProductFormView> {
                         ScrollViewKeyboardDismissBehavior.onDrag,
                     padding: const EdgeInsets.all(24),
                     children: [
+                      if (managedOnWebsite) ...[
+                        const ManagedOnWebsiteNotice(),
+                        const SizedBox(height: 16),
+                      ],
                       _buildImagePicker(context),
                       const SizedBox(height: 24),
                       TextFormField(
                         controller: _nameController,
+                        enabled: !managedOnWebsite,
                         decoration: InputDecoration(
                           labelText: l10n.productName,
                           border: OutlineInputBorder(),
@@ -366,6 +376,7 @@ class _ProductFormViewState extends State<ProductFormView> {
                             builder: (context, constraints) {
                               return DropdownMenu<String>(
                                 width: constraints.maxWidth,
+                                enabled: !managedOnWebsite,
                                 initialSelection: _selectedCategory,
                                 enableFilter: true,
                                 enableSearch: true,
@@ -395,6 +406,7 @@ class _ProductFormViewState extends State<ProductFormView> {
                       const SizedBox(height: 16),
                       TextFormField(
                         controller: _priceController,
+                        enabled: !managedOnWebsite,
                         decoration: InputDecoration(
                           labelText: l10n.price,
                           prefixText: '€ ',
@@ -455,6 +467,7 @@ class _ProductFormViewState extends State<ProductFormView> {
                         const SizedBox(height: 16),
                         TextFormField(
                           controller: _lowStockController,
+                          enabled: !managedOnWebsite,
                           decoration: InputDecoration(
                             labelText: l10n.lowStockThreshold,
                             border: OutlineInputBorder(),