feat(client): 标签打印预览弹窗（打印机选择 + 份数 + 所见即所得预览）

- 新增 LabelData 模型统一聚合单张标签字段（qrBytes/copies 等）
- 抽取 _renderLabelBitmap 共享位图绘制逻辑，TSPL 裸发与预览渲染完全一致
- 新增 renderLabelPreview / listLabelPrinters / detectDefaultPrinter 公开 API
- printProductLabel 新增 printerName 参数，透传到热敏裸发路径
- 新建 LabelPreviewDialog：缩略图条+大图主视图，打印机下拉+记忆（SharedPrefs）
  份数调整、勾选跳过、逐张打印进度状态显示
- 库存/商品详情/入库单 打标签 均接入预览弹窗，移除旧 _LabelPrintDialog

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

client/lib/screens/stock_out/stock_out_list_screen.dart

@@ -1,7 +1,6 @@
-import '../../repositories/product_repository.dart';
 import '../../core/utils/dialog_util.dart';
 import '../../core/errors/error_reporter.dart';
-import '../../core/utils/print_util.dart' show safePrint, printStockOutOrder, printProductLabel;
+import '../../core/utils/print_util.dart' show safePrint, printStockOutOrder;
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
@@ -920,149 +919,3 @@ class _StatusFilterDropdown extends StatelessWidget {
   }
 }
 
-class _LabelPrintDialog extends StatefulWidget {
-  final StockOutOrder order;
-  final ProductRepository productRepo;
-  final String shopName;
-  final String shopAddress;
-  final String shopPhone;
-  const _LabelPrintDialog({
-    required this.order,
-    required this.productRepo,
-    this.shopName = '',
-    this.shopAddress = '',
-    this.shopPhone = '',
-  });
-
-  @override
-  State<_LabelPrintDialog> createState() => _LabelPrintDialogState();
-}
-
-class _LabelPrintDialogState extends State<_LabelPrintDialog> {
-  late final List<bool> _selected;
-  bool _printing = false;
-  String _status = '';
-
-  @override
-  void initState() {
-    super.initState();
-    _selected = List.filled(widget.order.items.length, true);
-  }
-
-  Future<void> _print() async {
-    setState(() { _printing = true; _status = '正在打印...'; });
-    int done = 0;
-    for (int i = 0; i < widget.order.items.length; i++) {
-      if (!_selected[i]) continue;
-      final item = widget.order.items[i];
-      try {
-        final qrBytes = await widget.productRepo.getQRCodeBytes(item.productId);
-        await printProductLabel(
-          qrBytes: qrBytes,
-          name: item.productName ?? '',
-          code: item.productCode ?? '',
-          series: item.productSeries,
-          spec: item.productSpec,
-          shopName: widget.shopName,
-          shopAddress: widget.shopAddress,
-          shopPhone: widget.shopPhone,
-        );
-        done++;
-        if (mounted) setState(() => _status = '已打印 $done 张...');
-      } catch (e, st) {
-        reportError(e, st);
-        if (mounted) setState(() => _status = '第${i + 1}行打印失败：$e');
-      }
-    }
-    if (mounted) {
-      setState(() { _printing = false; _status = '完成，共打印 $done 张'; });
-    }
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    final items = widget.order.items;
-    return Dialog(
-      child: Container(
-        width: context.dialogWidth(520),
-        constraints: const BoxConstraints(maxHeight: 520),
-        child: Column(
-          crossAxisAlignment: CrossAxisAlignment.start,
-          children: [
-            Container(
-              padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 14),
-              decoration: const BoxDecoration(
-                color: AppTheme.primary,
-                borderRadius: BorderRadius.only(
-                  topLeft: Radius.circular(12),
-                  topRight: Radius.circular(12),
-                ),
-              ),
-              child: Row(
-                children: [
-                  const Text('打印商品标签',
-                      style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600, color: Colors.white)),
-                  const Spacer(),
-                  IconButton(
-                    icon: const Icon(Icons.close, color: Colors.white),
-                    onPressed: () => Navigator.of(context).pop(),
-                  ),
-                ],
-              ),
-            ),
-            Expanded(
-              child: ListView.separated(
-                padding: const EdgeInsets.symmetric(vertical: 8),
-                itemCount: items.length,
-                separatorBuilder: (_, __) => const Divider(height: 1),
-                itemBuilder: (_, i) {
-                  final item = items[i];
-                  return CheckboxListTile(
-                    value: _selected[i],
-                    onChanged: _printing
-                        ? null
-                        : (v) => setState(() => _selected[i] = v ?? false),
-                    title: Text(
-                      '${item.productCode ?? ''} ${item.productName ?? ''}',
-                      style: const TextStyle(fontSize: 13),
-                    ),
-                    subtitle: Text(
-                      '${item.productSeries ?? ''}  ${item.productSpec ?? ''}',
-                      style: const TextStyle(fontSize: 12, color: AppTheme.textSecondary),
-                    ),
-                    dense: true,
-                    controlAffinity: ListTileControlAffinity.leading,
-                  );
-                },
-              ),
-            ),
-            if (_status.isNotEmpty)
-              Padding(
-                padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 4),
-                child: Text(_status,
-                    style: const TextStyle(fontSize: 12, color: AppTheme.textSecondary)),
-              ),
-            Padding(
-              padding: const EdgeInsets.all(16),
-              child: Row(
-                mainAxisAlignment: MainAxisAlignment.end,
-                children: [
-                  TextButton(
-                    onPressed: () => Navigator.of(context).pop(),
-                    child: const Text('关闭'),
-                  ),
-                  const SizedBox(width: 8),
-                  ElevatedButton.icon(
-                    onPressed: (_printing || !_selected.contains(true)) ? null : _print,
-                    icon: const Icon(Icons.print_outlined, size: 16),
-                    label: Text(_printing ? '打印中...' : '打印选中'),
-                  ),
-                ],
-              ),
-            ),
-          ],
-        ),
-      ),
-    );
-  }
-}