feat: add an owner + sell screen

lib/ui/sell_page/widgets/scan_screen.dart

@@ -0,0 +1,73 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_svg/svg.dart';
+import 'package:mobile_scanner/mobile_scanner.dart';
+import 'package:seshat/ui/sell_page/view_model/sell_view_model.dart';
+import 'package:seshat/ui/sell_page/widgets/manual_scan_popup.dart';
+
+class ScanScreen extends StatefulWidget {
+  ScanScreen({super.key, required this.viewModel});
+
+  SellViewModel viewModel;
+
+  @override
+  State<ScanScreen> createState() => _ScanScreenState();
+}
+
+class _ScanScreenState extends State<ScanScreen> {
+  final MobileScannerController controller = MobileScannerController(
+    formats: [BarcodeFormat.ean13],
+    detectionTimeoutMs: 1000,
+  );
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    return Stack(
+      children: [
+        MobileScanner(
+          controller: controller,
+          onDetect: (barcodes) async {
+            widget.viewModel.showScan = false;
+            widget.viewModel.scanBook(barcodes);
+            controller.dispose();
+          },
+        ),
+        SafeArea(
+          child: Column(
+            children: [
+              IconButton(
+                onPressed: () {
+                  widget.viewModel.showScan = false;
+                },
+                icon: Icon(Icons.arrow_back),
+              ),
+            ],
+          ),
+        ),
+        Center(child: SvgPicture.asset('assets/scan-overlay.svg')),
+        Column(
+          mainAxisAlignment: MainAxisAlignment.end,
+          crossAxisAlignment: CrossAxisAlignment.center,
+          children: [
+            Center(
+              child: TextButton(
+                style: ButtonStyle(
+                  backgroundColor: WidgetStatePropertyAll(theme.cardColor),
+                ),
+                onPressed: () {
+                  showDialog(
+                    context: context,
+                    barrierDismissible: false,
+                    builder: (context) =>
+                        ManualScanPopup(viewModel: widget.viewModel),
+                  );
+                },
+                child: Text("Vendre un livre sans scanner"),
+              ),
+            ),
+            SizedBox(height: 5),
+          ],
+        ),
+      ],
+    );
+  }
+}