fix(client): 统一打印错误处理，失败时上报并弹提示

新增 safePrint 封装，所有打印调用点统一 catch 任意异常（含字体加载失败），
自动上报 error_reporter 并展示 SnackBar，不再静默失败。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/core/utils/print_util.dart

@@ -1,6 +1,8 @@
 import 'dart:typed_data';
+import 'package:flutter/material.dart';
 import '../../models/stock_in.dart';
 import '../../models/stock_out.dart';
+import '../errors/error_reporter.dart';
 import 'print_util_stub.dart'
     if (dart.library.js_interop) 'print_util_web.dart';
 
@@ -36,3 +38,18 @@ Future<void> printStockInOrder(StockInOrder order) =>
 
 Future<void> printStockOutOrder(StockOutOrder order) =>
     printStockOutOrderImpl(order);
+
+/// 统一打印入口：catch 任意异常，上报并弹 SnackBar 给用户。
+/// 用法：await safePrint(context, () => printStockInOrder(order));
+Future<void> safePrint(BuildContext context, Future<void> Function() fn) async {
+  try {
+    await fn();
+  } catch (e, st) {
+    reportError(e, st);
+    if (context.mounted) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('打印失败：$e'), backgroundColor: Colors.red),
+      );
+    }
+  }
+}

client/lib/core/utils/print_util_stub.dart

@@ -190,7 +190,6 @@ Future<void> printProductLabelImpl({
     ),
   ));
 
-  try {
     await Printing.layoutPdf(onLayout: (_) async => doc.save());
   } catch (e, st) {
     reportError(e, st);
@@ -430,7 +429,6 @@ Future<void> printStockInOrderImpl(StockInOrder order) async {
       ),
     ],
   ));
-  try {
     await Printing.layoutPdf(onLayout: (_) async => doc.save());
   } catch (e, st) {
     reportError(e, st);