feat(cost-center): 成本项编码改系统自动生成，补自动发货价格导入脚本

- 新建成本项目不再手填编码：后端按成本类型生成基础编码（auto_purchase /
  work_order_reward / manual_service / platform_fee / payment_fee /
  after_sales_loss / shipping_other / other_cost），重复时追加 _2、_3；
  接口显式传 code 时仍优先使用，兼容脚本导入
- 前端移除编码输入框，改为说明提示，创建成功提示展示生成的编码
- 新增 scripts/sync-affiliate-dash-prices.ts + scripts/data/affiliate-dash-prices.json：
  按上游 38 条自动发货价格补建 aff:<sku> 商品，并按 cost_amount（分）生成
  scope=product 的按件成本版本；价格变化时停用旧版本再插新版本
- 自动发货商品同步与价格导入的 attributes_json 改为合并，避免互相覆盖

apps/backend/src/services/admin/admin-cost-center-service.ts

@@ -25,6 +25,17 @@ const COST_TYPES = new Set([
   'shipping_other',
   'other',
 ])
+/** 成本项自动编码的基础名：按成本类型生成，重复时追加 _2、_3。 */
+const COST_ITEM_CODE_BASE: Record<string, string> = {
+  auto_purchase: 'auto_purchase',
+  work_order_reward: 'work_order_reward',
+  manual_service: 'manual_service',
+  platform_fee: 'platform_fee',
+  payment_fee: 'payment_fee',
+  after_sales_loss: 'after_sales_loss',
+  shipping_other: 'shipping_other',
+  other: 'other_cost',
+}
 const CARRIER_TYPES = new Set(['affiliate_dash', 'work_order', 'manual', 'shared'])
 const PRICING_MODES = new Set([
   'per_item',
@@ -1498,7 +1509,7 @@ export async function syncAdminAffiliateDashProducts() {
       SET carrier_type = 'affiliate_dash',
           canonical_name = EXCLUDED.canonical_name,
           unit_name = EXCLUDED.unit_name,
-          attributes_json = EXCLUDED.attributes_json,
+          attributes_json = product_catalog.attributes_json || EXCLUDED.attributes_json,
           updated_at = $1
       RETURNING (xmax = 0) AS inserted
     `,
@@ -2161,11 +2172,12 @@ export async function listAdminCostItems(payload: JsonObject = {}) {
 }
 
 export async function createAdminCostItem(payload: JsonObject, _session: AdminSession) {
-  const code = normalizeRequiredText(payload.code, '成本项编码', 64)
   const name = normalizeRequiredText(payload.name, '成本项名称', 120)
   const costType = normalizeStatus(payload.costType, COST_TYPES, null, '成本类型无效')
   const carrierType = normalizeStatus(payload.carrierType, CARRIER_TYPES, null, '成本载体无效')
   const pricingMode = normalizeStatus(payload.pricingMode, PRICING_MODES, null, '计价方式无效')
+  // 编码由系统生成（按成本类型 + 冲突序号）；显式传入时仍优先使用，兼容脚本导入。
+  const code = normalizeOptionalText(payload.code, 64) || (await generateCostItemCode(costType))
   const unitName = normalizeOptionalText(payload.unitName, 16) || '件'
   const currency = normalizeOptionalText(payload.currency, 8) || 'CNY'
   const status = normalizeStatus(payload.status, PRODUCT_STATUSES, 'active', '成本项状态无效')
@@ -2193,6 +2205,22 @@ export async function createAdminCostItem(payload: JsonObject, _session: AdminSe
   return { costItem: mapCostItem(inserted) }
 }
 
+async function generateCostItemCode(costType: string) {
+  const base = COST_ITEM_CODE_BASE[costType] || 'cost_item'
+  let candidate = base
+  let index = 2
+  for (let attempt = 0; attempt < 100; attempt += 1) {
+    const existing = await query<{ id: number }>(
+      'SELECT id FROM cost_items WHERE code = $1 LIMIT 1',
+      [candidate],
+    )
+    if (!existing.rows[0]) return candidate
+    candidate = `${base}_${index}`
+    index += 1
+  }
+  return `${base}_${Date.now()}`
+}
+
 export async function updateAdminCostItem(costItemId: number | string, payload: JsonObject) {
   const id = normalizeId(costItemId, '成本项 ID')
   const current = await getCostItemRow(id)