feat: Add receipt import functionality with file upload and parsing

- Implemented receipt file upload in ImportRepository with multipart request handling.
- Created ParsedReceiptItem model for parsed receipt data.
- Added ReceiptImportTab for user interface to upload and review receipts.
- Updated ImportScreen to include the new ReceiptImportTab alongside RecipeImportTab.
- Introduced flutter_bootstrap.js and index.html for web app initialization.
- Added wimp.wasm and flutter.js for enhanced web performance and capabilities.

flutter/lib/features/import/data/import_repository.dart

@@ -1,3 +1,4 @@
+import '../domain/parsed_receipt_item.dart';
 import 'dart:convert';
 import 'dart:typed_data';
 
@@ -12,6 +13,34 @@ import '../domain/quick_import_result.dart';
 ///   • [importFile] — multipart upload (PDF / image bytes, max 10 MB).
 ///   • [importUrl]  — JSON body with `{ input: url }`.
 class ImportRepository {
+    /// Upload a receipt file for parsing (Fas 6b).
+    /// Returns a list of parsed receipt items.
+    Future<List<ParsedReceiptItem>> importReceiptFile({
+      required Uint8List bytes,
+      required String filename,
+      String? token,
+    }) async {
+      final uri = Uri.parse('$_baseUrl/receipt-import');
+      final request = http.MultipartRequest('POST', uri);
+      if (token != null) {
+        request.headers['Authorization'] = 'Bearer $token';
+      }
+      request.files.add(
+        http.MultipartFile.fromBytes('file', bytes, filename: filename),
+      );
+      final streamed = await _client.send(request).timeout(
+        const Duration(seconds: 120),
+        onTimeout: () => throw ApiException(
+          type: ApiErrorType.network,
+          message: 'Importen tog för lång tid. Försök igen.',
+        ),
+      );
+      final response = await http.Response.fromStream(streamed);
+      final parsed = _parseResponse(response);
+      final items = (parsed['items'] as List?) ?? parsed as List?;
+      if (items == null) throw ApiException(type: ApiErrorType.unknown, message: 'Felaktigt svar från servern.');
+      return items.map((e) => ParsedReceiptItem.fromJson(e as Map<String, dynamic>)).toList();
+    }
   final http.Client _client;
   final String _baseUrl;