feat(client): 搜索选项支持拼音和首字母

使用 lpinyin 预计算每个选项的全拼和首字母，
输入 wl 可匹配「五粮液」，输入 maotai 可匹配「茅台」。

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

client/lib/widgets/searchable_option_field.dart

@@ -1,11 +1,27 @@
 import 'package:flutter/material.dart';
+import 'package:lpinyin/lpinyin.dart';
 import '../core/theme/app_theme.dart';
 
 class OptionItem {
   final int id;
   final String name;
   final String? code;
-  const OptionItem({required this.id, required this.name, this.code});
+  // 拼音索引，构造时预计算
+  late final String _fullPinyin;
+  late final String _initials;
+
+  OptionItem({required this.id, required this.name, this.code}) {
+    _fullPinyin = PinyinHelper.getPinyinE(name, separator: '', defPinyin: '').toLowerCase();
+    _initials   = PinyinHelper.getShortPinyin(name).toLowerCase();
+  }
+
+  bool matches(String kw) {
+    final k = kw.toLowerCase();
+    return name.toLowerCase().contains(k) ||
+        (_fullPinyin.isNotEmpty && _fullPinyin.contains(k)) ||
+        (_initials.isNotEmpty && _initials.contains(k)) ||
+        (code?.toLowerCase().contains(k) ?? false);
+  }
 }
 
 /// 点击后弹出搜索对话框的下拉选择框
@@ -112,9 +128,7 @@ class _SearchDialogState extends State<_SearchDialog> {
   Widget build(BuildContext context) {
     final filtered = _keyword.isEmpty
         ? widget.options
-        : widget.options.where((o) =>
-            o.name.toLowerCase().contains(_keyword.toLowerCase()) ||
-            (o.code?.toLowerCase().contains(_keyword.toLowerCase()) ?? false)).toList();
+        : widget.options.where((o) => o.matches(_keyword)).toList();
 
     return AlertDialog(
       title: Text(widget.title, style: const TextStyle(fontSize: 16)),