feat(admin): 后台新增「抖音码速达」配置面板

- 新增 Tab：/admin/platform-shops?tab=douyinMashida
- 面板字段：enabled / baseUrl / uid / secret / certLink / afterVerifyLink /
  afterVerifyMessage / messageType / timeoutMs / handledTopics(tags)
- 密钥脱敏：出参 secret 永远为空，输入框未编辑时对外 value 恒为 ''，
  掩码不会污染后端「空串=保留原值」语义
- 顶部展示 ready 状态，未就绪时用 Alert 列出缺哪几项；
  始终展示平台侧要配的推送地址（可复制）
- baseUrl 命中本地地址时提示「当前指向本地网关桩，不会请求真实码速达」
- 把 AdminPlatformShopsPage 内联的 SecretFieldControl 抽成共享组件
  （函数体与原实现逐字节一致，8 处既有调用点参数不变）

apps/frontend/src/components/admin/SecretFieldControl.tsx

@@ -0,0 +1,158 @@
+import { EditOutlined, UndoOutlined } from '@ant-design/icons'
+import { Button, Input, Space, Tag, Typography } from 'antd'
+import { useState } from 'react'
+
+/**
+ * 脱敏密钥输入控件。
+ *
+ * 已配置时只显示掩码 + 「修改」按钮，点开后才出现密码输入框；
+ * 未编辑时对外 value 恒为 ''，避免把掩码值当成新密钥回填提交。
+ */
+export function SecretFieldControl({
+  label,
+  field,
+  masked,
+  hasSecret,
+  value,
+  onChange,
+  placeholder,
+}: {
+  label: string
+  field: string
+  masked?: string | undefined
+  hasSecret?: boolean | undefined
+  value: string
+  onChange: (value: string) => void
+  placeholder?: string | undefined
+}) {
+  const [isEditing, setIsEditing] = useState(false)
+  const [draft, setDraft] = useState('')
+
+  const isStaged = Boolean(value && value.trim())
+  const configured = Boolean(hasSecret || (masked && masked.trim()))
+
+  function handleStartEdit() {
+    setDraft('')
+    setIsEditing(true)
+  }
+
+  function handleApply() {
+    const trimmed = draft.trim()
+    if (trimmed) {
+      onChange(trimmed)
+      setIsEditing(false)
+      setDraft('')
+    }
+  }
+
+  function handleCancel() {
+    setDraft('')
+    setIsEditing(false)
+  }
+
+  function handleRevert() {
+    onChange('')
+    setDraft('')
+    setIsEditing(false)
+  }
+
+  return (
+    <div style={{ minWidth: 0 }}>
+      <div
+        style={{
+          display: 'flex',
+          justifyContent: 'space-between',
+          alignItems: 'center',
+          marginBottom: 4,
+          minHeight: 22,
+        }}
+      >
+        <Typography.Text type="secondary">{label}</Typography.Text>
+        {isStaged ? (
+          <Button
+            type="link"
+            size="small"
+            icon={<UndoOutlined />}
+            style={{ padding: 0, height: 'auto', fontSize: 12 }}
+            onClick={handleRevert}
+          >
+            撤销修改
+          </Button>
+        ) : null}
+      </div>
+
+      {isEditing ? (
+        <Space.Compact style={{ width: '100%' }}>
+          <Input.Password
+            autoFocus
+            autoComplete="new-password"
+            data-1p-ignore="true"
+            data-lpignore="true"
+            data-bwignore="true"
+            data-form-type="other"
+            name={`secure_field_${field}`}
+            id={`secure_field_${field}`}
+            placeholder={placeholder || `输入新 ${label}（留空不修改）`}
+            value={draft}
+            onChange={(e) => setDraft(e.target.value)}
+            onPressEnter={handleApply}
+          />
+          <Button type="primary" onClick={handleApply} disabled={!draft.trim()}>
+            应用
+          </Button>
+          <Button onClick={handleCancel}>取消</Button>
+        </Space.Compact>
+      ) : (
+        <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
+          <div
+            style={{
+              flex: 1,
+              minWidth: 0,
+              height: 32,
+              display: 'flex',
+              alignItems: 'center',
+              justifyContent: 'space-between',
+              padding: '0 11px',
+              background: '#fafafa',
+              border: isStaged ? '1px dashed #faad14' : '1px solid #d9d9d9',
+              borderRadius: 6,
+              fontFamily:
+                'ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace',
+              fontSize: 12,
+              color: isStaged ? '#d46b08' : configured ? '#262626' : '#8c8c8c',
+              userSelect: 'none',
+              overflow: 'hidden',
+            }}
+          >
+            <span
+              style={{
+                textOverflow: 'ellipsis',
+                overflow: 'hidden',
+                whiteSpace: 'nowrap',
+                marginRight: 8,
+              }}
+            >
+              {isStaged
+                ? '已输入新密钥（待保存）'
+                : masked || (configured ? '••••••••••••••••' : '未配置')}
+            </span>
+            {isStaged ? (
+              <Tag color="warning" style={{ margin: 0, flexShrink: 0 }}>
+                待保存
+              </Tag>
+            ) : configured ? (
+              <Tag color="success" style={{ margin: 0, flexShrink: 0 }}>
+                已配置
+              </Tag>
+            ) : (
+              <Tag style={{ margin: 0, flexShrink: 0 }}>未配置</Tag>
+            )}
+          </div>
+          <Button icon={<EditOutlined />} onClick={handleStartEdit} style={{ flexShrink: 0 }}>
+            {configured ? '修改' : '设置'}
+          </Button>
+        </div>
+      )}
+    </div>
+  )
+}