refactor(client): 抽公用 PangolinFieldBox 统一输入框 + 根治填充两色接缝

根因:主题 inputDecorationTheme 设了 filled:true/fillColor:bg,自定义容器里嵌
TextField 时内层自铺 bg 底,与容器底色(搜索框 bgSubtle / 登录 surface)不一致 →
两端一色中间另一色接缝(节点搜索框最明显,登录/兑换框也有隐患)。

- kBareInput 加 filled:false:内层 TextField 不再自铺底,底色统一交给外层容器。
- 新增 widgets/pangolin_field.dart:PangolinFieldBox(圆角容器 + 底色 + 可选描边/
  聚焦光环 + 标签 + 前置图标 + 后置 widget)+ bareInputDecoration() 助手。
- 三处输入框统一改用:节点搜索框、登录/注册字段(_field)、兑换码输入框。
- 重生成 auth_login(dark/light)+ desktop_redeem golden(均人工核对外观正确)。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/widgets/account_screens.dart

@@ -10,6 +10,7 @@ import '../models/device.dart';
 import '../pangolin_theme.dart';
 import '../services/device_identity.dart';
 import 'adaptive_menu.dart';
+import 'pangolin_field.dart';
 import '../services/auth_api.dart';
 import '../state/account_providers.dart';
 import 'pangolin_button.dart';
@@ -384,15 +385,13 @@ class _RedeemScreenState extends ConsumerState<RedeemScreen> {
               ])
             else
               Row(children: [
-                Expanded(child: Container(
-                  padding: const EdgeInsets.symmetric(horizontal: 14),
-                  decoration: BoxDecoration(color: c.bg, borderRadius: BorderRadius.circular(PangolinRadius.md), border: Border.all(color: c.borderStrong, width: 1.5)),
+                Expanded(child: PangolinFieldBox(
+                  fill: c.bg,
                   child: TextField(
                     controller: _code,
                     textCapitalization: TextCapitalization.characters,
                     style: PangolinText.mono.copyWith(color: c.fg1, letterSpacing: 1.5),
-                    // kBareInput 关掉主题边框/填充泄漏（聚焦时橙框错位/被裁），聚焦态交给外层 Border。
-                    decoration: kBareInput.copyWith(contentPadding: const EdgeInsets.symmetric(vertical: 13), hintText: t.redeemPh, hintStyle: PangolinText.sm.copyWith(color: c.fg3)),
+                    decoration: bareInputDecoration(contentPadding: const EdgeInsets.symmetric(vertical: 13), hintText: t.redeemPh, hintStyle: PangolinText.sm.copyWith(color: c.fg3)),
                     onChanged: (_) => setState(() {}),
                   ),
                 )),

client/lib/widgets/auth_screen.dart

@@ -13,6 +13,7 @@ import '../services/auth_api.dart';
 import '../services/device_identity.dart';
 import '../state/auth_provider.dart';
 import 'pangolin_button.dart';
+import 'pangolin_field.dart';
 import 'pangolin_icons.dart';
 import 'pangolin_logo.dart';
 
@@ -342,29 +343,13 @@ class _AuthScreenState extends ConsumerState<AuthScreen>
         ),
       );
 
-  // 输入字段:标签 + 图标 + 聚焦态(accent 边 + 光环)。
-  Widget _field(PangolinScheme c, {required IconData icon, required String label, required bool focused, required Widget child}) {
-    return Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
-      Text(label, style: PangolinText.caption.copyWith(color: c.fg2, fontWeight: FontWeight.w600)),
-      const SizedBox(height: 7),
-      AnimatedContainer(
-        duration: const Duration(milliseconds: 160),
-        padding: const EdgeInsets.symmetric(horizontal: 14),
-        decoration: BoxDecoration(
-          color: c.surface,
-          borderRadius: BorderRadius.circular(PangolinRadius.md),
-          border: Border.all(color: focused ? c.accent : c.borderStrong, width: 1.5),
-          boxShadow: focused ? [BoxShadow(color: c.ring, spreadRadius: 3)] : null,
-        ),
-        child: Row(children: [Icon(icon, size: 18, color: c.fg3), const SizedBox(width: 10), Expanded(child: child)]),
-      ),
-    ]);
-  }
+  // 输入字段:标签 + 图标 + 聚焦态(accent 边 + 光环)。统一走 PangolinFieldBox。
+  Widget _field(PangolinScheme c, {required IconData icon, required String label, required bool focused, required Widget child}) =>
+      PangolinFieldBox(label: label, leading: icon, focused: focused, child: child);
 
-  // kBareInput 关掉主题 inputDecorationTheme 的边框/填充泄漏（否则聚焦时橙色
-  // OutlineInputBorder 会画到内层 TextField 上、与外层容器错位/被裁）。
+  // 内层裸装饰(无边框无填充,底色交给 PangolinFieldBox)。
   InputDecoration get _bare =>
-      kBareInput.copyWith(contentPadding: const EdgeInsets.symmetric(vertical: 13));
+      bareInputDecoration(contentPadding: const EdgeInsets.symmetric(vertical: 13));
 
   // 密码输入 + 显示/隐藏切换(眼睛按钮)。
   Widget _pwInput(PangolinScheme c, String hint, {VoidCallback? onSubmit}) => Row(children: [

client/lib/widgets/pangolin_field.dart

@@ -0,0 +1,88 @@
+// pangolin_field.dart — 统一输入框容器组件。
+//
+// 圆角容器(底色 + 可选描边/聚焦光环 + 可选上方标签 + 前置图标 + 后置 widget),
+// 内层放一个用 [bareInputDecoration] 的 TextField。底色由本容器统一提供,内层不再
+// 自铺填充 → 杜绝「容器底色 ≠ TextField filled 底色」的两端一色中间另一色接缝。
+// 聚焦态(accent 边 + 光环)也由容器负责。搜索框/兑换码/登录注册输入框共用此组件。
+import 'package:flutter/material.dart';
+
+import '../pangolin_theme.dart';
+
+/// 内层 TextField 用的「裸」装饰:无边框、无填充。底色/边框/聚焦都交给 [PangolinFieldBox]。
+InputDecoration bareInputDecoration({
+  EdgeInsetsGeometry contentPadding = const EdgeInsets.symmetric(vertical: 12),
+  String? hintText,
+  TextStyle? hintStyle,
+  String? counterText,
+}) =>
+    kBareInput.copyWith(
+      contentPadding: contentPadding,
+      hintText: hintText,
+      hintStyle: hintStyle,
+      counterText: counterText,
+    );
+
+class PangolinFieldBox extends StatelessWidget {
+  const PangolinFieldBox({
+    super.key,
+    required this.child,
+    this.fill,
+    this.label,
+    this.leading,
+    this.trailing,
+    this.focused = false,
+    this.bordered = true,
+    this.horizontalPadding = 14,
+  });
+
+  /// 内层输入(用 [bareInputDecoration] 构造装饰)。
+  final Widget child;
+
+  /// 容器底色;默认 [PangolinScheme.surface]。搜索框传 bgSubtle、兑换码传 bg。
+  final Color? fill;
+
+  /// 上方标签(可空)。登录/注册字段用。
+  final String? label;
+
+  /// 前置图标(可空)。
+  final IconData? leading;
+
+  /// 后置 widget(可空):如密码显示切换、发送验证码。
+  final Widget? trailing;
+
+  /// 聚焦态:accent 边 + 光环(仅 [bordered] 时生效)。
+  final bool focused;
+
+  /// 是否描边。搜索框传 false(只有底色,无边)。
+  final bool bordered;
+
+  final double horizontalPadding;
+
+  @override
+  Widget build(BuildContext context) {
+    final c = context.pangolin;
+    final box = AnimatedContainer(
+      duration: const Duration(milliseconds: 160),
+      padding: EdgeInsets.symmetric(horizontal: horizontalPadding),
+      decoration: BoxDecoration(
+        color: fill ?? c.surface,
+        borderRadius: BorderRadius.circular(PangolinRadius.md),
+        border: bordered
+            ? Border.all(color: focused ? c.accent : c.borderStrong, width: 1.5)
+            : null,
+        boxShadow: (bordered && focused) ? [BoxShadow(color: c.ring, spreadRadius: 3)] : null,
+      ),
+      child: Row(children: [
+        if (leading != null) ...[Icon(leading, size: 18, color: c.fg3), const SizedBox(width: 10)],
+        Expanded(child: child),
+        if (trailing != null) trailing!,
+      ]),
+    );
+    if (label == null) return box;
+    return Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
+      Text(label!, style: PangolinText.caption.copyWith(color: c.fg2, fontWeight: FontWeight.w600)),
+      const SizedBox(height: 7),
+      box,
+    ]);
+  }
+}