feat(receipt-import): enhance bread category detection and improve session management

Co-authored-by: Copilot <copilot@github.com>

flutter/lib/features/import/presentation/receipt_import_tab.dart

@@ -66,6 +66,30 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
   void initState() {
     super.initState();
     _loadProducts();
+    _restoreSession();
+  }
+
+  Future<void> _restoreSession() async {
+    final notifier = ref.read(receiptImportSessionProvider.notifier);
+    await notifier.restore();
+    final session = ref.read(receiptImportSessionProvider);
+    if (!mounted || session?.fileBytes == null) return;
+
+    final fileName =
+        session?.fileName ?? 'kvitto.${session?.fileExtension ?? 'pdf'}';
+    final bytes = session!.fileBytes!;
+    setState(() {
+      _pickedFile = PlatformFile(
+        name: fileName,
+        size: bytes.length,
+        bytes: bytes,
+        extension: session.fileExtension,
+      );
+    });
+
+    if (session.items != null) {
+      await _loadInventory();
+    }
   }
 
   int? _categoryIdForProduct(int? productId) {
@@ -244,11 +268,18 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
     ref.read(receiptImportSessionProvider.notifier).setFile(
       file.bytes!,
       file.extension?.toLowerCase() ?? '',
+      fileName: file.name,
     );
   }
 
   Future<void> _submit() async {
-    if (_pickedFile == null) return;
+    final session = ref.read(receiptImportSessionProvider);
+    final submitBytes = _pickedFile?.bytes ?? session?.fileBytes;
+    if (submitBytes == null) return;
+
+    final submitFileName =
+        _pickedFile?.name ?? session?.fileName ?? 'kvitto.${session?.fileExtension ?? 'pdf'}';
+
     setState(() { _isLoading = true; });
     // Obs: setFile() i _pickFile har redan placerat bytes i session; clear() behövs ej här
 
@@ -256,8 +287,8 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
       final token = await ref.read(authStateProvider.future);
       final repo = ref.read(importRepositoryProvider);
       final items = await repo.importReceiptFile(
-        bytes: _pickedFile!.bytes!,
-        filename: _pickedFile!.name,
+        bytes: submitBytes,
+        filename: submitFileName,
         token: token,
       );
       if (!mounted) return;
@@ -508,7 +539,12 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
     }
   }
 
-  bool get _canSubmit => !_isLoading && _pickedFile?.bytes != null;
+  bool get _canSubmit {
+    if (_isLoading) return false;
+    if (_pickedFile?.bytes != null) return true;
+    final session = ref.read(receiptImportSessionProvider);
+    return session?.fileBytes != null;
+  }
   int get _selectedCount => _selected.values.where((v) => v).length;
 
   // ── Kvittobild / PDF-förhandsvisning ───────────────────────────────────────
@@ -570,6 +606,9 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
     final session = ref.watch(receiptImportSessionProvider);
     final theme = Theme.of(context);
     final items = session?.items;
+    final selectedFileName = _pickedFile?.name ?? session?.fileName;
+    final selectedFileSizeBytes =
+      _pickedFile?.size ?? session?.fileBytes?.length;
 
     return SingleChildScrollView(
       padding: const EdgeInsets.all(16),
@@ -584,12 +623,12 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
           OutlinedButton.icon(
             onPressed: _isLoading ? null : _pickFile,
             icon: const Icon(Icons.attach_file),
-            label: Text(_pickedFile == null ? 'Välj kvittofil' : _pickedFile!.name),
+            label: Text(selectedFileName == null ? 'Välj kvittofil' : selectedFileName),
           ),
-          if (_pickedFile != null) ...[
+          if (selectedFileSizeBytes != null) ...[
             const SizedBox(height: 8),
             Text(
-              '${(_pickedFile!.size / 1024).round()} KB',
+              '${(selectedFileSizeBytes / 1024).round()} KB',
               style: theme.textTheme.bodySmall?.copyWith(color: theme.colorScheme.outline),
             ),
           ],