feat: add an owner + sell screen

lib/ui/sell_page/widgets/manual_scan_popup.dart

@@ -0,0 +1,39 @@
+import 'package:flutter/material.dart';
+import 'package:seshat/ui/sell_page/view_model/sell_view_model.dart';
+
+class ManualScanPopup extends StatelessWidget {
+  ManualScanPopup({required this.viewModel});
+
+  final SellViewModel viewModel;
+
+  @override
+  Widget build(BuildContext context) {
+    return AlertDialog(
+      title: Text("Recherche manuelle"),
+      content: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          TextField(
+            decoration: InputDecoration(
+              labelText: "Rechercher",
+              suffixIcon: IconButton(
+                onPressed: () {},
+                icon: Icon(Icons.arrow_forward),
+              ),
+              border: OutlineInputBorder(),
+            ),
+          ),
+          SizedBox(height: 200),
+        ],
+      ),
+      actions: [
+        TextButton(
+          onPressed: () {
+            Navigator.of(context).pop();
+          },
+          child: Text("Annuler"),
+        ),
+      ],
+    );
+  }
+}