feat(client): 名称/系列/规格可搜索下拉 + 修复打印状态提示

- 新增 SearchableOptionField 组件：点击弹出带搜索框的对话框，支持实时过滤
- 入库/出库表单名称、系列、规格列全部替换为可搜索选择器
- 打印按钮加步骤状态提示（正在准备字体→生成PDF→打开打印）+ catch 错误展示

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

client/lib/screens/products/product_detail_screen.dart

@@ -512,6 +512,7 @@ class _QRCodeDialogState extends ConsumerState<_QRCodeDialog> {
   late Future<Uint8List> _future;
   Uint8List? _bytes;
   bool _printing = false;
+  String _printStatus = '';
 
   @override
   void initState() {
@@ -526,9 +527,10 @@ class _QRCodeDialogState extends ConsumerState<_QRCodeDialog> {
 
   Future<void> _print() async {
     if (_bytes == null || _printing) return;
-    setState(() => _printing = true);
+    setState(() { _printing = true; _printStatus = '正在准备字体...'; });
     try {
       final fontData = await rootBundle.load('assets/fonts/NotoSansSC-Regular.ttf');
+      if (mounted) setState(() => _printStatus = '正在生成 PDF...');
       final font = pw.Font.ttf(fontData);
       final p = widget.product;
       final doc = pw.Document();
@@ -553,9 +555,16 @@ class _QRCodeDialogState extends ConsumerState<_QRCodeDialog> {
           ),
         ),
       ));
+      if (mounted) setState(() => _printStatus = '正在打开打印...');
       await Printing.layoutPdf(onLayout: (_) async => doc.save());
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('打印失败：$e'), backgroundColor: Colors.red),
+        );
+      }
     } finally {
-      if (mounted) setState(() => _printing = false);
+      if (mounted) setState(() { _printing = false; _printStatus = ''; });
     }
   }
 
@@ -591,7 +600,9 @@ class _QRCodeDialogState extends ConsumerState<_QRCodeDialog> {
                   width: 14, height: 14,
                   child: CircularProgressIndicator(strokeWidth: 2, color: Colors.white))
               : const Icon(Icons.print, size: 16),
-          label: const Text('打印'),
+          label: Text(_printing
+              ? (_printStatus.isNotEmpty ? _printStatus : '准备中...')
+              : '打印'),
         ),
       ],
     );