feat: enhance receipt import functionality with category selection and PDF opening support

flutter/lib/core/utils/pdf_opener.dart

@@ -0,0 +1,6 @@
+import 'dart:typed_data';
+
+import 'pdf_opener_stub.dart'
+    if (dart.library.js_interop) 'pdf_opener_web.dart' as impl;
+
+Future<bool> openPdfBytes(Uint8List bytes) => impl.openPdfBytes(bytes);

flutter/lib/core/utils/pdf_opener_stub.dart

@@ -0,0 +1,3 @@
+import 'dart:typed_data';
+
+Future<bool> openPdfBytes(Uint8List bytes) async => false;

flutter/lib/core/utils/pdf_opener_web.dart

@@ -0,0 +1,19 @@
+import 'dart:js_interop';
+import 'dart:typed_data';
+
+import 'package:web/web.dart' as web;
+
+Future<bool> openPdfBytes(Uint8List bytes) async {
+  final blob = web.Blob(
+    [bytes.toJS].toJS,
+    web.BlobPropertyBag(type: 'application/pdf'),
+  );
+  final url = web.URL.createObjectURL(blob);
+  final openedWindow = web.window.open(url, '_blank', 'noopener,noreferrer');
+  if (openedWindow == null) {
+    web.URL.revokeObjectURL(url);
+    return false;
+  }
+  web.URL.revokeObjectURL(url);
+  return true;
+}