feat(wallet): 钱包系统替代配额系统，新增支付与退款机制

- 新增钱包余额管理、充值、扣费、退款完整流程
- 新增支付网关抽象层（支持手动/支付宝/微信）
- 用量计费从配额系统迁移到钱包余额扣费
- 新增管理员钱包管理与支付订单管理页面
- 新增用户钱包中心页面
- 移除独立 Key 锁定机制，统一由钱包余额控制
- 新增相关 API 路由、序列化器与数据库迁移
- 新增钱包、支付、退款相关测试

frontend/src/utils/walletDisplay.ts

@@ -0,0 +1,153 @@
+export function walletStatusLabel(status: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    active: '正常',
+    suspended: '已冻结',
+    closed: '已关闭',
+  }
+  if (!status) return '未知'
+  return labels[status] || status
+}
+
+export function formatWalletCurrency(
+  value: number | null | undefined,
+  options?: { decimals?: number }
+): string {
+  const decimals = options?.decimals ?? 2
+  const amount = Number(value ?? 0)
+  return `$${amount.toFixed(decimals)}`
+}
+
+export function walletStatusBadge(status: string | null | undefined): string {
+  if (status === 'active') return 'success'
+  if (status === 'suspended') return 'warning'
+  if (status === 'closed') return 'destructive'
+  return 'secondary'
+}
+
+export function walletTransactionCategoryLabel(category: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    recharge: '充值',
+    gift: '赠款',
+    adjust: '调账',
+    refund: '退款',
+  }
+  if (!category) return '未知'
+  return labels[category] || category
+}
+
+export function walletTransactionReasonLabel(reasonCode: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    topup_admin_manual: '人工充值',
+    topup_gateway: '支付充值',
+    topup_card_code: '卡密充值',
+    gift_initial: '初始赠款',
+    gift_campaign: '活动赠款',
+    gift_expire_reclaim: '赠款回收',
+    adjust_admin: '人工调账',
+    adjust_system: '系统调账',
+    refund_out: '退款扣减',
+    refund_revert: '退款回补',
+  }
+  if (!reasonCode) return '未知'
+  return labels[reasonCode] || reasonCode
+}
+
+export function paymentMethodLabel(method: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    alipay: '支付宝',
+    wechat: '微信支付',
+    admin_manual: '人工充值',
+    card_code: '充值卡',
+    gift_code: '礼品卡',
+    card_recharge: '卡密充值',
+    bank_transfer: '银行转账',
+    offline: '线下转账',
+  }
+  if (!method) return '-'
+  return labels[method] || method
+}
+
+export function paymentStatusLabel(status: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    pending: '待支付',
+    paid: '已支付',
+    credited: '已到账',
+    failed: '支付失败',
+    expired: '已过期',
+    refunding: '退款中',
+    refunded: '已退款',
+  }
+  if (!status) return '未知'
+  return labels[status] || status
+}
+
+export function walletLinkTypeLabel(type: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    payment_order: '充值订单',
+    refund_request: '退款申请',
+    admin_action: '后台操作',
+    system_task: '系统任务',
+    campaign: '活动批次',
+    usage: '用量记录',
+  }
+  if (!type) return '-'
+  return labels[type] || '其他'
+}
+
+export function paymentStatusBadge(status: string | null | undefined): string {
+  if (status === 'credited' || status === 'refunded') return 'success'
+  if (status === 'paid' || status === 'refunding') return 'outline'
+  if (status === 'pending') return 'secondary'
+  if (status === 'expired') return 'warning'
+  if (status === 'failed') return 'destructive'
+  return 'secondary'
+}
+
+export function refundModeLabel(mode: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    original_channel: '原路退回',
+    offline_payout: '线下打款',
+  }
+  if (!mode) return '-'
+  return labels[mode] || mode
+}
+
+export function refundStatusLabel(status: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    pending_approval: '待审批',
+    approved: '已审批',
+    processing: '处理中',
+    succeeded: '已完成',
+    failed: '已失败',
+    cancelled: '已取消',
+  }
+  if (!status) return '未知'
+  return labels[status] || status
+}
+
+export function refundStatusBadge(status: string | null | undefined): string {
+  if (status === 'succeeded') return 'success'
+  if (status === 'processing') return 'outline'
+  if (status === 'pending_approval' || status === 'approved') return 'secondary'
+  if (status === 'failed' || status === 'cancelled') return 'destructive'
+  return 'secondary'
+}
+
+export function callbackStatusLabel(status: string | null | undefined): string {
+  const labels: Record<string, string> = {
+    processed: '已处理',
+    duplicate: '重复回调',
+    ignored: '已忽略',
+    invalid_signature: '验签失败',
+    error: '处理失败',
+  }
+  if (!status) return '未知'
+  return labels[status] || status
+}
+
+export function callbackStatusBadge(status: string | null | undefined): string {
+  if (status === 'processed') return 'success'
+  if (status === 'duplicate' || status === 'ignored') return 'secondary'
+  if (status === 'invalid_signature' || status === 'error') return 'destructive'
+  return 'outline'
+}