feat(pickup): 新增管理员线下提号功能

- 新建 admin_pickups 表独立于 rental_orders，不污染订单状态机与财务统计口径
- 提号中/已完成/已取消三态：创建锁定账号，完成时给卖家钱包加可用余额并下架 listing，取消解锁账号
- 完成时 listing 置 completed，复用现有 listingLockedForOwnerMutation 拦截再上架
- 管理端提号管理页（列表/创建/完成/取消/可提号账号搜索）+ 卖家端提号记录页
- 财务仪表盘新增线下提号独立统计块，与正常订单口径分离
- 钱包流水 label、状态标签、菜单入口同步补齐
- 优化卖家服务悬浮菜单为一行四个，尺寸与配色对齐买家服务

backend/migrations/000021_admin_pickups.sql

@@ -0,0 +1,32 @@
+-- +goose Up
+
+CREATE TABLE admin_pickups (
+  id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+  pickup_no VARCHAR(64) NOT NULL COMMENT '提号编号 PK+时间+随机',
+  listing_id BIGINT UNSIGNED NOT NULL COMMENT '关联的发布项',
+  account_id BIGINT UNSIGNED NOT NULL COMMENT '关联的游戏账号',
+  owner_id BIGINT UNSIGNED NOT NULL COMMENT '卖家(号主)',
+  admin_id BIGINT UNSIGNED NOT NULL COMMENT '操作管理员',
+  platform VARCHAR(32) NOT NULL DEFAULT '' COMMENT '线下交易渠道(微信/QQ/闲鱼等)',
+  settle_amount_cent BIGINT NOT NULL DEFAULT 0 COMMENT '完成时结算金额(分)',
+  status VARCHAR(20) NOT NULL DEFAULT 'picking_up' COMMENT '状态: picking_up提号中/completed已完成/cancelled已取消',
+  remark VARCHAR(255) NOT NULL DEFAULT '' COMMENT '创建备注',
+  complete_remark VARCHAR(255) NOT NULL DEFAULT '' COMMENT '完成备注',
+  created_at DATETIME NOT NULL,
+  completed_at DATETIME NULL,
+  cancelled_at DATETIME NULL,
+  PRIMARY KEY (id),
+  UNIQUE KEY uk_pickup_no (pickup_no),
+  KEY idx_listing (listing_id),
+  KEY idx_owner (owner_id),
+  KEY idx_status (status),
+  KEY idx_created (created_at)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='管理员线下提号记录，独立于 rental_orders';
+
+INSERT INTO permissions (code, name, resource, action)
+VALUES ('order:pickup', '管理员提号', 'order', 'pickup');
+
+-- +goose Down
+
+DROP TABLE IF EXISTS admin_pickups;
+DELETE FROM permissions WHERE code = 'order:pickup';